JRS Tutorials

PHYSICS

JRS Tutorials, Durgakund, Varanasi-221005, Ph No.(0542) 2311922, 2311777

JRS TUTORIALSELECTROSTATICS (12-PMT)

DPP-05 : ELECTRIC FIELD1. Figure shows a metal body of mass M charged positively. P is a point in front of the body. The

electric field at point P due to the body M is Ep. Now a negative change –q is placed at point Pand it experiences a force F. then(A) Ep = F/q

(B) Ep < F/q(C) Ep > F/q

(D) None of these.2. Two charges 9e and 3e are placed at a distance r. The distance of the point where the

electric field intensity will be zero is:

(A)

31r

from 9e charge (B)

3/11r

from 9e charge

(C)

31r

from 3e charge (D)

3/11r

from 3e charge.

3. Two point charges +8q and –2q are located at x = 0 and x = L respectively. The location of apoint on the x axis at which the net electric field due to these two point charges is zero is

(A) 2 L (B) L/4 (C) 8 L (D) 4 L4. Charges 2Q and –Q are placed as shown in figure. The point at which electric field intensity is

zero will be:(A) Somewhere between –Q and 2Q(B) Somewhere on the left of –Q(C) Somewhere on the right of 2Q(D) Somewhere on the right bisector of line joining –Q and 2Q

5. Three charge particles +2q (a,0), +q (0,a) and q (0, a) are placed on the circumference of acircle of radius ‘a’ and centre at origin . The electric field at the centre ‘O’ of the circle will be

(A) 20a4q2

(B) 20a4q2

(C) 20a4

q22 (D) 2

0a4q

6. Four point charges are placed at the corners of a square with diagonal 2a as shown. What is the

total electric field at the center of the square?

(A) kq/a2 at an angle 45° above the +x axis

(B) kq/a2 at an angle 45° below the –x axis

(C) 9kq/a2 at an angle 45° above the +x axis

(D) 3kq/a2 at an angle 45° below the +x axis

PHYSICS


7. Four electrical charges are arranged on the corners of a 10 cm square as shown.What would be the

direction of the resulting electric field at the center point P?

(A) (B)

(C) (D)

8. Four charges are placed on the circumference of a circle of radius R, 90° apart as shown in thefig. The electric field strength at the centre of the circle is

(A) 20 R

Q524

1 , making angle tan–12 with the – ve x-axis.

(B) 20 R

Q524

1 , making angle tan–12 with the + ve y-axis.

(C) 20 R

Q244

1 , making angle tan–1

21

with the – ve x-axis.

(D) 20 R

Q244


21

with the + ve y-axis.

9. Figures below show regular hexagons, with charges at the vertices. In which of the followingcases the electric field at the centre is not zero

(1) (2)

q q

q

qq

q

q –q

q

–q

q

q(3) (4)

2q 2q

qq

2q q

2q

q

q

2q 2q 2q

(A) 4 (B) 3 (C) 2 (D) 110. Two charged particles (-q) and (-2q) are placed at the origin A and B of an isosceles right angle

triangle AOB, as shown in figure. The value of charge Q placed at the point P for which theelectric field at ‘O’ will be zero is,(A) Q = 3q/2(B) Q = 2q/3

A P

B O a

a

–q

–2q(C) Q = 3q

(D) Not possible11. Four point charges q, q, Q and 2Q are placed in order at the corners A, B, C and D of a

square. If the field at the midpoint of CD is zero then the value of Qq

is

(A) 1 (B) 25

(C) 5

22(D)

255

PHYSICS


12. Figures shows four situations in which charged particles are at equal distances from the origin.If E1, E2, E3 and E4 be the magnitude of the net electric fields at the origin in four situations (i),(ii), (iii) and (iv) respectively, then -

(i)

–5q

2q –3q

y

xO (ii)

–5q

3q –2q

y

xO (iii)

4q –q

y

xO

5q

(iv)

q –4q

y

x O

4q

–q

(A) E1 = E2 = E3 = E4 (B) E1 = E2 > E3 > E4 (C) E1 < E2 < E3 = E4 (D) E1 > E2 = E3 < E4

13. Charges q, 2q, 4q, 8q, ..... are placed along x-axis at r, 2r, 4r, 8r, ..... from origin respectively.The net electric field at origin is

(A) Infinite (B) 20

q4 r (C) 2

0

q2 r (D) 2

0

q8 r

14. A regular polygon has n sides each of length l. Each corner of the polygon is at a distance r

from the centre. Identical charges each equal to q are placed at (n – 1) corners of the polygon.

What is the electric field at the centre of the polygon

(A) 204 r

qn (B) 2

04 lqn

(C) 204

1rq

(D) 204

1lq

15. A point charge 50C is located in the x-y plane at the position vector m)j3i2(r0 . The

electric field (in N/C) at the point of position vector m)j5i8(r , in vector from is equal to

(A) 90 )j4i3( (B) 90 )j4i3( (C) 900 )j4i3( (D) 900 )j4i3(

16. The variation of electric field between the two charges q1 and q2 along the line joining thecharges is plotted against distance from q1 (taking rightward direction of electric field as positive)as shown in the figure. Then

(A) q1 and q2 are positive and q1 < q2

(B) q1 and q2 are positive and q1 > q2 q1 q2r

E

(C) q1 is positive and q2 is negative and q1 < q2

(D) q1 and q2 are negative and q1 < q2

17. A ring of radius R is charged uniformly with a charge + Q . The electric field at any point onits axis at a distance r from the circumference of the ring will be:–

(A) 2 2 3/2

KQr

(R r ) (B) 2

KQ

r(C) 1 / 22 2

3

KQr R

r (D) 3

KQr

R

18. A ring of radius R, has charge –Q distributed uniformly over it. A charge q is placed at the centreof the ring such that the electric field becomes zero at a point on the axis of the ring distant ‘R’from the centre of the ring. The value of charge q is

(A) Q 32

(B) Q 24

(C) Q 23

(D) Q 34

PHYSICS


ANSWER KEY

1. B 2. B 3. A 4. B 5. C 6. B

7. B 8. A 9. C 10. D 11. D 12. A

13. C 14. C 15. D 16. A 17. C 18. B


PHYSICS


DPP-03 : Properties of Charge and Coulomb’s Law (Subjective)

1. Calculate protonic charge in 100cc. of water.[Ans. 5.4 × 106 cb.]

2.. Can a body have a charge (a) 0.32 × 10–18 C (b) 0.64 × 10–20 C (c) 4.8 × 10–21 C[Ans. (a) Yes, (b) No , (c) No]

3. When a piece of polythene is rubbed with wool, a charge of – 2 × 10–7 C is developed on polythene.What is the amount of mass, which is transfered to polythene.

[Ans. 11.38 × 10–19 kg ]

4. 1012 – particles (Nuclei of helium) per second falls on a neutral sphere, calculate time in whichsphere gets charged by 2C.

[Ans. 6.25 sec ]

5.. In a neutral sphere 5 × 1021 electrons are present. If 10 percent electrons are removed, then calculatethe charge on sphere.

[Ans. 80 C]6. The electrostatic force of repulsion between two positive ions carrying equal charge having

separation 5Å is 3.7 × 10–9 N. How many electrons are missing from each. [Ans. 2]

7. The force between two point charges in air is 100 N. Calculate the force if the distance between themis increased by 50%.

[Ans. 44 N]8. Two identical metal sphere carry charges of + q and – 2q respectively. When the sphere are separated

by a distance r, the force between them is F. Now the spheres are allowed to touch and then movedback to same separation. Find the force of repulsion between them.

[Ans. F/8]9. Two insulating small spheres are rubbed against each other and are then kept at a distance of 4m

apart. If they attract each other with a force of 3.5 N, then(i) Calculate the charge on each sphere, and(ii) Calculate the number of electrons transferred from one sphere to another during the rubbing.

[Ans. (i) 8 × 10–5 C (ii) 5 × 1014]10. A particle of mass m carrying charge q1 is revolving around a fixed charge –q2 in a circular

path of radius r. Calculate the period of revolution and its speed also.

[Ans. T = 4r 21

0

qqmr

; V = mr4qq

0

21

]


PHYSICS11. (i) Two charged particles having charge 4.0 × 10–6 C and mass 24 × 10–3 Kg each are joined

by an insulating string of length 1 m and the system is kept on a smooth horizontal table.Find the tension in the string.(ii) If suddenly string is cut then what is the acceleration of each block?(iii) Are they having equal acceleration?[Ans. (i) 0.144 N (ii) 6 m/s2 (iii) No (Magnitude is same but direction is different) ]

12. Three equal point charges of charge +q are moving along a circle of radius R and a pointcharge –2q is also placed at the centre of circle as (shown in figure), if charges are revolvingwith constant and same speed then calculate speed.

[Ans.

312

Rmkqv

2

]

13. The figure shows four situations in which charges as indicated (q>0) are fixed on an axis.How many situations is there a point to the left of the charges where an electron would be inequilibrium?

+q –4q

+4q –q

(1)

(3)

–q +4q

–4q q

(2)

(4)

[Ans. 2]14. Six charges are kept at the vertices of a regular hexagon as shown in the figure. If magnitude of

force applied by +Q on +q charge is F, then net electric force on the +Q is nF. Find the value of n.+q

-2q

+3q

-4q

+q

+Q-3q

[Ans. 9]15. A point charge qA = + 100 µc is placed at point A (1, 0, 2) m and an another point charge

qB = +200µc is placed at point B (4, 4, 2) m. Find :(i) Magnitude of Electrostatic interaction force acting between them

(ii) Find AF

(force on A due to B) and BF

(force on B due to A) in vector form

[Ans. (i) 7.2 N (ii) BF

= 7.2

j

54i

53

N ; AF

= 7.2

j

54i

53

N ]

PHYSICS


JRS TUTORIALSVECTOR (11th PMT)

DPP-011. A physical quantity which has a direction :

(A) cannot be a vector (B) must be a vector (C) must be a scalar (D) may be a vector

2. The magnitude of a vector cannot be :

(A) positive (B) unity (C) negative (D) zero

3. Which of the following vector is equal as that of 1 m

(A) 1 m (B) 2 m

(C) 1 m

(D) 1 m

4. The forces, each numerically equal to 5 N, are acting as shown in the Figure. Find the anglebetween forces?(A) 90°

(B) 120°

(C) 0°

(D) 60°

5. For the figure shown.

(A) A B C

(B) B C A

(C) C A B

(D) A B C 0

6. Six vectors, a through f

have the mangitudes and directions indicated in the figure.Which of

the following statements is true ?

`

(A) b + c = f

(B) d + c = f

(C) d + e = f

(D) b + e = f

PHYSICS


7. Column-I show vector diagram relating three vectors a, b and c . Match the vector equation in

column-II, with vector diagram in column-I and choose the correct option :

Column-I Column-II

(I)a

bc(P) 0)cb(a

(II)a

cb (Q) acb

(III)a b

c(R) cba

(IV)b

ca (S) cba

(A) (I)-R ; (II)-S ; (III)-Q ; (IV)-P (B) (I)-P ; (II)-R ; (III)-S ; (IV)-Q

(C) (I)-Q ; (II)-S ; (III)-P ; (IV)-R (D) (I)-R ; (II)-S ; (III)-P ; (IV)-Q

8. If the magnitude of velocity v is 2 2 ms–1. Then v is

(A) –1 –1ˆ ˆv (2 ms ) i + (2 ms ) j

(B) –1 –1ˆ ˆv (2 ms ) i – (2 ms ) j

45°

Y

X

vY'

X'

(C) –1 –1ˆ ˆv (2 ms ) i – (2 ms ) j

(D) –1 –1ˆ ˆv (2 ms ) i + (2 ms ) j

9. If the magnitude of a is 20 ms–2. Then a is

(A) –2 –2ˆ â (10 3 ms ) i + (10 ms ) j

(B) –2 –2ˆ â (10 ms ) i + (10 3 ms ) j 60°

Y

X

a

Y'

X'

(C) –2 –2ˆ â (10 ms ) i – (10 ms ) j

(D) –2 –2ˆ â (10 3 ms ) i + (10 ms ) j

PHYSICS


10. The magnitude of momentum p of a paticle is 40 N-s.The momentum p of the particle is

(A) ˆ ˆp (20 N-s) i (20 3 N-s) j

(B) ˆ ˆp (20 N-s) i (20 3 N-s) j

30°

Y

X

pY'

X'

(C) ˆ ˆp (20 3 N-s) i (20 N-s) j

(D) ˆ ˆp (20 3 N-s) i (20 N-s) j

11. A man moves 20 m in a direction 30° North of West. Represent displacement in the form of unit

vectors assuming east as positive X axis and north as positive Y axis.

(A) ˆ ˆs (10 m) i (10 3 m) j (B) ˆ ˆs ( 10 3 m) i (10 m) j

(C) ˆ ˆs (10 3 m) i (10 m) j (D) ˆ ˆs (10m) i (10 3 m) j

12. A man moves 10 m in a direction 30° East of North.The displacement of man is [assuming east

as positive X axis and north as positive Y axis]

(A) ˆ ˆs 5 3 i 5 j m

(B) ˆ ˆs 5i 5 3 j m

(C) ˆ ˆs 5 3i 5 j m

(D) ˆ ˆs 5 i 5 3 j m

13. A person pushes a box kept on a horizontal surface with force of 100 N. In unit vector notationforce F

can be expressed as :

(A) 100 ˆ ˆ(i j)

(B) 100 ˆ ˆ(i j)

45°

y

xF

(C) 250 ˆ ˆ(i j)

(D) 50 2 ˆ ˆ(i j)

14. Just after firing, a bullet is found to move at an angle of 37° to horizontal. Its acceleration is 10m/s2 downwards. Find the component of acceleration in the direction of the velocity.

(A) – 6 m/s2

(B) – 4 m/s2

(C) – 8 m/s2

(D) – 5 m/s2

15. A man walks 40 m North, then 30 m East and then 40 m South. What is his displacement fromthe starting point ?(A) 30 m East (B) 150 m West (C) 40 m West (D) 150 m East

16. A person moves 30 m North then 20 m East then 30 2 m South West. His displacement fromthe original position is(A) 15 m East (B) 28 m South (C) 10 m West (D) 14 m South-West

PHYSICS


17. A particle moves along a path ABCD as shown in the figure. Then the magnitude of netdisplacement of the particle from position A to D is :(A) 10 m

(B) 25 m(C) 9 m(D) 27 m

18. Find the resultant of three vectors OA

, OB

and OC

and each of magnitude R(A) 2R(B) R(1 + 2 )(D) R 2

(D) R( 2 – 1)

19. Find resultant force as vector in ˆ ˆai bj format.

(A) ˆ ˆ225 i 300 j

(B) ˆ ˆ475 i 900 j

(C) ˆ ˆ475 i 600 j

(D) ˆ ˆ475 i 900 j

20. Two horizontal forces of magnitudes 10 N & P N act on a particle. The force of magnitude 10 Nacts due west & the force of magnitude P N acts on a bearing of 30° east of north as shown infigure. The resultant of these two force acts due north. Find the magnitude of this resultant.(A) 310 N

(B) 20 N(C)10 N(D) 10 / 3 N

21. Three forces acting on a body are shown in the figure. To have the resultant force only along the

y-direction, the magnitude of the minimum additional force needed is:

(A) 0.5N (B) 1.5N (C) 3 N

4(D) 3N

PHYSICS


22. As shown in figure, find the magnitude of the unknown forces X and Y if sum of all forces iszero.(A) 5N, 5N(B) 5N, 10N(C) 10N, 5N(D) 10N, 10N

23. An insect crawls 10 m towards east, turns to its right, crawls 8 m, and again turns to its right,Now crawling a distance of 2 m it turns to its right and stop after moving 2 m more. Find its netdisplacement.(A) 10 m , 37° S of E (B) 10 m , 37° E of S(C) 5 m , 37° S of E (D) 5 m , 37° W of N

24. A sail boat sails 2 km due East, 5 km 37o South of East and finally an unknown displacement .If the final displacement of the boat from the starting point is 6 km due East, the third displace-ment is ______(A) 3 km North (B) 3 km South (C) 4 km South (D) 4 km East

ANSWER KEY

VECTOR DPP-01

1. D 2. C 3. C 4. B 5. C 6. C

7. D 8. C 9. B 10. B 11. B 12. D

13. C 14. A 15. A 16. C 17. D 18. B

19. D 20. A 21. A 22. B 23. A 24. A


PHYSICS


DPP-02 : Coulomb’s Law1. The diagram shows the arrangement of three small uniformly charged spheres A, B and C.

The arrows indicate the direction of the electrostatic forces acting between the spheres(forexample, the left arrow on sphere A indicates the electrostatic force on sphere A due tosphere B). At least two of the spheres are positively charged. Which sphere, if any, could benegatively charged ?

A

CB

(A) sphere A (B) sphere B (C) sphere C (D) no sphere2. Two conducting spheres of radii R each are given equal charges +Q and are kept such that

their centre are at distance r (>R). The force of attraction (F) between them is:

(A) 2

2

rKQ

(B) 2

2

)R2r(KQ

(C) 2

2

2

2

)R2r(KQF

rKQ

(D) 2

2

)R2r(KQ > F > 2r

KQ

3. Two point charges Q and 2Q are placed r distance apart. By keeping value of distance constant,

if value of each charge increases by 50% then electric force increases by-

(A) 225% (B) 125% (C) 450% (D) 250%4. When two charges are equal q each, force they exert on each other is F. When one of the charge

is doubled, then 2q charge exerts a force 2F on charge q. The force exerted by q on 2q is

(A) F (B) 2F (C) 4

F (D) 2F

5. Two particles having charges q1 and q2 when kept at a certain distance, exert a force F on eachother. If the distance between the two particles is reduced to half and the charge on each particleis doubled then the force between the particles would be(A) 2F (B) 4 F (C) 8 F (D) 16 F

6. Two point charge +2C & +6C repel each other with force of 12 N. It a charge –4C is given toboth the charges, the force of interaction becomes(A) 4 N attractive (B) 4 N repulsive (C) 8 N attractive (D) 8 N repulsive


PHYSICS7. Two charges equal in magnitude and opposite in polarity are placed at a certain distance apart

and force acting between them is F. If 75% charge of one is transferred to another, then the forcebetween the charges becomes

(A) F

16 (B) 9F16 (C) F (D)

15F16

8. Two charges q1 and q2 separated by a dielectric of dielectric constant 4 repel each other witha force of 10N. Another charge q3 is placed between q1 and q2 such that the distance of q3

from q1 is 1/4 times the distance of q3 from q2. Now, the force of repulsion between q1 andq2 is

(A) 10 N (B) 10 q1 (C) 2

1

4q 10 Nq

(D) 2

1

qq10

9. Two similar very small conducting spheres having charges 40 mC and –20 mC are somedistance apart. Now they are touched and kept at same distance. The ratio of the initial to thefinal force between them is :(A) 8 : 1 (B) 4 : 1 (C) 1 : 8 (D) 1 : 1

10. Two spherical conductors B and C having equal radii and carrying equal charges on them repeleach other with a force F when kept apart at some distance. A third spherical conductor havingsame radius as that of B but uncharged is brought in contact with B, then brought in contactwith C and finally removed away from both. The new force of repulsion between B and C is(A) F/4 (B) 3F/4 (C) F/8 (D) 3F/8 [AIEEE-2004]

11. Two small, identical spheres having +Q and – Q charge are kept at a certain distance such thatforce F acts between the two spheres. If in the middle of two spheres, another similar spherehaving +Q charge is kept, then it experience a force in magnitude and direction as(A) Zero having no direction (B) 8F towards +Q charge(C) 8F towards – Q charge (D) 4F towards +Q charge

12. Two point charges q and 4q are located at a distance 2a apart. A charge Q is placed alongthe line joining them as shown in figure so that force on this becomes zero. The distancebetween charges q and Q is

q Q

2a

4q

(A) 3a

(B) 4a (C) 3

2a(D)

2a

13. Two equally charged, identical metal spheres A and B repel each other with a force ‘F. Thespheres are kept fixed with a distance r between them. A third identical, but uncharged sphere Cis brought in contact with A and then placed at the mid-point of the line joining A and B. Themagnitude of the net electric force on C is(A) F (B) 3F/4 (C) F/2 (D) F/4


PHYSICS14. A certain charge Q is divided at first into two parts, (q) and (Q-q). Later on the charges

are placed at a certain distance. If the force of interaction between the two charges ismaximum then-(A) (Q/q) = (4/1) (B) (Q/q) = (2/1) (C) (Q/q) = (3/1) (D) (Q/q) = (5/1)

15. Two point charges –Q and +2Q are placed at a distance R apart. Where should a third pointcharge be placed so that it is in equilibrium –(A) at a point on the right of +2Q.(B) at a point on the left of charge –Q(C) between –Q and +2Q(D) at a point on a line perpendicular to the line joining –Q and +2Q

16. Two point charges + 9e and +e are kept 16 cm. apart to each other. Where should a third chargeq be placed between them so that the system remains in the equilibrium state :–(A) 24 cm from + 9e (B) 12 cm from + 9e (C) 24 cm from + e (D) 12 cm from + e

17. Two small spheres with mass 1m and 2m hang from massless, insulating threads of length 1

and 2 . The two spheres carry charges 1q and 2q respectively. The spheres hang such that

they are on same horizontal level and the threads are inclined to the vertical at angles 1 and

2 . Which of the condition is required if 1 = 2 .

11

22

m ,q1 1 m ,q2 2

(A) 1 2m m (B) 1 2q q (C) 1 = 2 (D) 1 2

1 2

q qm m

18. Two small balls, each having equal positive charge Q are suspended by two insulating strings ofequal length L from a hook fixed to a stand. If the whole set-up is transferred to a satellite inorbit around the earth, the tension in each string is equal to

L L

q qm m

(A) zero (B) 2LkQ

(C) 2

2

L2kQ (D) 2

2

L4kQ


PHYSICS19. Two small metallic spheres each of mass ‘m’ are suspended together with strings of length ‘l’

and placed together. When a quantum of charge ‘q’ is transferred to each the strings make an

angle of 900 with each other. The value of ‘q’ is

(A) mg0 (B) mg2 0 (C) mg4 0 (D) 08 mg

20. In the given figure two tiny conducting balls of identical mass m and identical charge q havenon-conducting threads of equal length L. Assume that is so small that tan = sin, then forequilibrium x is equal to

x

L L

q q

(A) 31

0

2

mg2Lq

(B)

31

0

2

mg2qL

(C)

31

0

22

mg4Lq

(D)

31

0

2

mg4Lq

21. Two pith balls carrying equal charges are suspended from a common point by strings of equallength, the equilibrium separation between them is r. Now the strings are rigidly clamped at halfthe height. The equilibrium separation between the balls now become : [NEET 2013]

r

y

r

y/2

(A)

2r

3 (B)

3r2

(C)

3r2

(D) 2

2r

22. Two particles, each of mass 10 g and having charge of 1C are in equilibrium on a horizontaltable at a distance of 50 cm. The coefficient of friction between the particles and the table is(A) 0.18 (B) 0.54 (C) 0.36 (D) 0.72

23. A particle of charge –q & mass m moves in a circular orbit about a fixed charge +Q a circle ofradius r and time period T. Which of following may be correct ?

(A) 23 Tr (B) 2/32 Tr (C) 3/23 Tr (D) None of these.


PHYSICS24. Two particle of equal mass m and charge q are placed at a distance of 16 cm. They do not

experience any force. The value of qm is

(A) 04 G (B) 0

G

(C)0

G4 (D) 04 G

25. With a rise in temperature, the dielectric constant K of a liquid

(A) increases (B) decreases (C) constant (D) none of these

26. Dimensional formula for dielectric constant

(A) MºLºTº (B) ML2T-2 (C) M1L2T-2A-1 (D) M-1L-3T4A2

27. Two point charges placed at a distance r in air exert a force F on each other. The value ofdistance R at which they experience force 4F when placed in a medium of dielectric constantK = 16 is :(A) r (B) r/4 (C) r/8 (D) 2r

28. Two point charges in air at a distance of 20 cm. from each other interact with a certain force.At what distance from each other should these charges be placed in oil of relative permittivity5 to obtain the same force of interaction –(A) 8.94 × 10–2 m (B) 0.894 × 10–2 m (C) 89.4 × 10–2 m (D) 8.94 × 102 m

29. Two point charges are placed at distance r between them and have force F between them isvacuum. A dielectric of constant K having thickness t < r is placed between them. How thedistance between the charges be changed so that force between them remains the same. Thenew distance is

(A) r – t + Kt

(B) r – t + K t (C) Kttr (D) r + t - K t.

30. Two identical charged spheres are suspended by strings of equal lengths. The strings make anangle of 30º with each other. When suspended in a liquid of density 0.8 g cm–3, the angleremains the same. If density of the material of the sphere is 1.6 g cm–3, the dielectric constant ofthe liquid is [AIEEE-2010](A) 4 (B) 3 (C) 2 (D) 1

ANSWER KEYELECTROSTATICS DPP-02

1. A 2. C 3. B 4. D 5. D 6. A

7. A 8. A 9. A 10. D 11. C 12. C

13. A 14. B 15. B 16. B 17. A 18. D

19. D 20. A 21. A 22. C 23. A 24. D

25. B 26. A 27. C 28. A 30. C


PHYSICS

JRS TUTORIALSELECTROSTATICS (12-PMT)DPP-01 : Charge and its properties

1. A body can be negatively charged by(A) Giving excess of electrons to it (B) Removing some electrons from it(C) Giving some protons to it (D) Removing some neutrons from it

2. On charging two metallic spheres of same mass-[I] Mass of positively charged sphere will be more[II] Mass of positively charged sphere will be less[III] Mass of negatively charged sphere will be more[IV] Mass of negatively charged will be lessWhich of above is/are correct ?(A) I, II (B) II, III (C) III, IV (D) I, IV

3. In Millikan's oil drop experiment, which of the following charges can be present on the oildrops–(A) 1.5 e, e (B) 2e, 1.6 x 10–19 C(C) 2e, 1.6 x 10–19 C, 2.5e (D) 0.1e, charge equal to that on –particles

4. Which of the following charge is not possible(A) 1.6 × 10–18 C (B) 1.6 × 10–19 C (C) 1.6 × 10–20 C (D) 1.6 C

5. A conductor has 1914.4 10 C positive charge. The conductor has(A) 9 electrons in excess (B) 27 electrons in excess(C) 9 electrons in short (D) 27 electrons in short

6. A body has a negative charge of 0.2 C . If body has 2.25×1012 protons, then number of

electrons present in the body will be(A) 121.25 10 (B) 122.25 10 (C) 121 10 (D) 123.50 10

7. An accelerated or deaccelerated charge produces-(A) Electric field only(B) Magnetic field only(C) Localised electric and magnetic fields(D) Electric and magnetic fields that radiates energy

8. Mark out of the correct option.(A) The total charge of the universe is constant.(B) The total positive charge of the universe is constant.(C) The total negative charge of the universe is constant(D) The total number of charged particles in the universe is constant.


PHYSICS9. Which of the following is a sure test of electrification?

(A) attraction (B) repulsion (C) induction (D) friction10. Electric charges A and B repel each other electric charge B and C also repel other. If A and C are

hold close together, they will(A) attract (B) repel(C) neither attract nor repel (D) none of these.

11. An electron at rest has a charge of 1.6 × 10–19 C. It starts moving with a velocity v = c/2,where c is the speed of light, then the new charge on it is -

(A) 1.6 10–19 C (B)1.6 10–19 112 2

C

(C) 19

2

1.6 10

112

C (D)1.6 10–19211

2 C

12. An uncharged metal object M is insulated from its surroundings. A positively charged metalsphere S is then brought near to M. Which diagram best illustrates the resultant distributionsof charge on S and M?

(A)

+

+

++++

+

+++

S M (B)

+

+

++

+

+++

S M

(C)

+

+

++

+

+++

S M (D)

+

+

++++

+

+++

S M

13. Two uncharged balls A and B, each very light and coated with a conducting material, hangvertically side by side just touching each other. A positively-charged glass rod is brought nearball A without touching it. Now A and B are separated and then the glass rod is removed. IfQA and QB represent the electric charges on A and B, respectively, you conclude that(A) QA < 0 and QB < 0; (B) QA < 0 and QB > 0;(C) QA > 0 and QB < 0; (D) QA > 0 and QB > 0;

14. A neutral spherical metallic object A is placed near a finite metal plate B carrying a positivecharge. The electric force on the object will be:(A) away from the plate B (B) towards the plate B(C) parallel to the plate B (D) zero

15. A soap bubble is given charge, then its radius

(A) decreases (B) increases (C) remains unchanged (D) depends on nature of charge


PHYSICS16. In the absence of other conductors, the surface charge density

(A) Is proportional to the charge on the conductor and its surface area(B) Inversely proportional to the charge and directly proportional to the surface area(C) Directly proportional to the charge and inversely proportional to the surface area(D) Inversely proportional to the charge and the surface area

17. An electroscope is given a positive charge, causing its foil leaves to separate.When an object is

brought near the top plate of the electroscope, the foils separate even further. We could conclude

(A) that the object is positively charged.

(B) that the object is electrically neutral.

(C) that the object is negatively charged.

(D) only that the object is charged.18. The evacuated negatively charged electroscope exposed to X-rays for a short period. Then

(A) The leaves will diverge further (B) The divergence of leaves will not be affected(C) The leaves will collapse (D) The leaves will melt

19. A glass rod rubbed with silk is used to charge a gold leaf electroscope then charged electroscope(not evacuated) is exposed to X-rays for a short period. Then(A) The leaves will diverge further (B) The divergence of leaves will not be affected(C) The leaves will collapse (D) The leaves will melt

20. An isolated solid metallic sphere is charged with +Q charge .The distribution of their +Qcharge on the sphere will be(A) uniform but on the surface alone (B) non uniform but on the surface alone(C) uniform inside the volume (D) non uniform inside the volume

21. The net charge given to an isolated conducting solid sphere:(A) must be distributed uniformly on the surface (B) may be distributed uniformly on the surface(C) must be distributed uniformly in the volume (D) may be distributed uniformly in the volume.

22. The net charge given to a solid insulating sphere:

(A) must be distributed uniformly in its volume

(B) may be distributed uniformly in its volume

(C) must be distributed uniformly on its surface

(D) the distribution will depend upon whether other charges are present or not.23. A cube of side 5 cm has a charge of 6C. The surface density of charge is

(A) 100 Cm–2 (B) 200Cm–2 (C) 300 Cm–2 (D) 400 Cm–2

24. 64 small drops of mercury, each of radius 'r' and charge q are combined to form a big drop. Theratio of the surface density of the charge of each small drop to that of a big drop is :–(A) 4 : 1 (B) 1 : 4 (C) 1 : 64 (D) 64 : 1


PHYSICS

ANSWER KEY PHYSICS DPP-01

1. A 2. B 3. B 4. C 5. C 6. D

7. D 8. A 9. B 10. B 11. A 12. C

13. B 14. B 15. B 16. C 17. A 18. C

19. C 20. A 21. A 22. B 23. D 24. B

JRS Tutorials, Durgakund, Varanasi-221005, Ph No. (0542) 2311777, 2311922, 9794757100, 317347706

JRS TUTORIALS CHEMISTRY 20-21

Solid State XII – (IIT and PMT)–DPP-2

1. The formula for determination of density of unit cell is

1. 303

cmgMNNa −

××

2. 3

03 cmg

NaMN −

×× 3. 3

0

3

cmgNNMa −

×× 4. 3

30 cmg

NaNM −

××

2. The packing efficiency of two dimensional square unit cell shown

below is

1. 32.97 % 2. 68%

3. 74% 4. 78.5%

3. A metal crystallises in a face centred cubic structure. If the edge length of its unit cell is

'a', the closest approach between two atoms in metallic crystal will be :-

1. 2a 2. a22 3. a2 4. 2

a

4. Body centered cubic lattice has a coordination number of 1. 4 2. 8 3. 12 4. 6

5. The element crystallizes in a body centered cubic lattice and the edge of the unit cell is 0.351 nm. The density is 0.533 g/cm3. What is the atomic weight?

1. 12.0 2. 6.94 3. 9.01 4. 10.8

6. An element crystallizes in a structure having fcc unit cell of an edge 200 pm. Calculate the density, if 100g of this element contains 12 × 1023 atoms

1. 41.66 g/cm3 2. 4. 166 g/cm3 3. 10.25 g/cm3 4. 1.025 g/cm3 7. The number of close neighbour in a body centred cubic lattice of identical sphere is 1. 8 2. 6 3. 4 4. 2 8. In the closest packed structure of a metallic lattice, the number of nearest neighbours

of a metallic atom is 1. Twelve 2. Four 3. Eight 4. Six 9. The number of atoms in 100 gm of an bcc crystal with density d = 10 g/cm3 and cell

edge equal to 100 pm, is equal to 1.

25104× 2. 25103× 3.

25102× 4. 25101×

10. The number of atoms in primitive cubic unit cell, body-centred cubic unit cell and face-

centred cubic unit cell are A, B and C, respectively. Select the correct values.

A B C A B C

1. 1, 2, 3 2. 1, 2, 4

3. 1, 1, 3 4. 2, 3, 4

L


2

11. The following crystallographic data were obtained for a protein. Volume of unit cube = 1.50 × 10–19 cm3, Density = 1.35 g cm–3 Z = 4 and protein fraction = 0.75. Thus, molar mass of protein is 1. 2.3 × 104 g mol–1 2. 3.048 × 104 g mol–1 3. 1.725 × 104 g mol–1 4. None of these 12. A element is having body centred unit cell arrangement. Length of body diagonal is

350 pm. Density of unit cell is 6 gm/cm3. Find how many atoms are present in 500 gm of element.

1. 20 NA 2. 25 NA 3. 34 NA 4. 40 NA 13. A metal crystallises in f.c.c. lattice with unit cell edge length of 4 . If 100 gm of this

metal contains 3 × 1023 atom, its density is 1. 1.44 gm/cm3 2. 14.4 gm/cm3 3. 10.4 gm/cm3 4. 20.8 gm/cm3

14. What are the number of atoms per unit cell and the number of nearest neighbours in a

sample cubic structure? 1. 1, 6 2. 4, 12 3. 2, 8 4. 2, 6 15. % of empty space in body centered cubic unit cell is nearly 1. 52.36 2. 68 3. 32 4. 26 16. Lithium has a bcc structure. Its density is 530 kg m–3 and its atomic mass is 6.94 gmol–1.

Calculate the edge length of a unit cell of Lithium metal. (NA = 6.02 × 1023) 1. 154 pm 2. 352 pm 3. 527 pm 4. 264 pm

17. A solid has a structure in which W atoms are located at the corners of a cubic lattice,

O atoms at the centres of edges and Na atom at the centre of the cube. The formula of the compound is

1. NaWO2 2. NaWO3 3. Na2WO3 4. NaWO4

18. A metal crystallizes with a face-centred cubic lattice. The edge of the unit cell is 408 pm. The diameter of the metal atom is

1. 288 pm 2. 408 pm 3. 144 pm 4. 204 pm

Answer DPP-2 Q.No. 1 2 3 4 5 6 7 8 9 10 Ans 2 4 4 2 2 1 1 1 3 2

Q.No. 11 12 13 14 15 16 17 18 Ans 2 3 4 1 3 2 2 1




1. Which of the following is not a crystalline solid ? 1. Common salt 2. Sugar 3. Iron 4. Rubber 2. A pseudo solid is : 1. Glass 2. pitch 3. KCl 4. Glass and pitch both 3. Solid CO2 is an example of, 1. Ionic crystal 2. Covalent crystal 3. Metallic crystal 4. Molecular crystal 4. A molecular crystalline solid, 1. is very hard 2. is volatile 3. has a high melting point 4. is a good conductor 5. Select the correct statement 1. Crystalline solids are anisotropic 2. Amorphous solids are isotropic 3. Both 1 and 2 4. None of the above 6. Amorphous materials are infact considered as 1. supercooled liquids 2. spercooled solids 3. covalent network 4. molecular crystals 7. The sharp melting point of crystalline solids compared to amorphous solids is due to 1. same arrangement of constituent particles in different directions 2. different arrangement of constituent particles in different directions

3. a regular arrangement of constituent particles observed over a long distance in the crystal lattice

4. a regular arrangement of constituent particles observed over a short distance in the crystal lattice

8. As it cools, olive oil solidifies and forms a solid over a wide range of temperature.

Which term best describes the solid? 1. Ionic 2. Covalent network 3. Metallic 4. amorphous solid 9. Which of the following can be regarded as molecular solids? 1. SiC 2. AlN 3. C(diamond) 4. Ne 10. A solid can be characterized by 1. definite mass, volume and shape 2. short intermolecular distances 3. strong intermolecular forces 4. All of the above 11. Which of the following are the correct axial distances and axial angles for rhombohedral

system ? 1. a = b = c, α =β = γ ≠ 90° 2. a = b ≠ c, α =β = γ = 90° 3. a ≠ b = c, α =β = γ = 90° 4. a ≠ b ≠ c, α ≠ β ≠ γ ≠ 90°


2 12. Select incorrect statement for polar molecular solids,

1. molecules have polar covalent bonds 2. molecules are held by relatively stronger dipole-dipole interactions 3. molecules are held by weak London forces 4. higher melting point as compared to non-polar molecular solids, is observed 13. a ≠ b ≠ c, α = γ = 90° β ≠ 90° represents 1. tetragonal system 2. orthorhombic system 3. monoclinic system 4. triclinic system 14. Bravais lattices are of, 1. 10 types 2. 8 types 3. 7 types 4. 14 types 15. In a simple cubic cell, each point on a corner is shared by, 1. 2 unit cells 2. 1 unit cell 3. 8 unit cells 4. 4 unit cells 16. In face centred cubic cell, an atom at the face centres is shared by, 1. 4 units cells 2. 2 unit cells 3. One unit cell 4. 6 unit cells 17. In a body centred cubic cell, an atom at the body centre is shared by, 1. 1 unit cell 2. 2 unit cell 3. 3 unit cells 4. 4 unit cells 18. Match Column A with B and select the correct option. Column A Column B

A. Ionic solid I. ZnS B. Metallic solid II. Au C. Covalent solid III. Diamond) D. Molecular solid IV. Ice 1. A - I, B - II, C - IV, D - III 2. A - I, B - II, C - III, D - IV 3. A - III, B - II, C - I, D - IV

4. A - II, B - IV, C - I, D - III

Answer DPP-1 Q.No. 1 2 3 4 5 6 7 8 9 10 Ans 4 4 4 2 3 1 3 4 4 4

Q.No. 11 12 13 14 15 16 17 18 Ans 1 3 3 4 3 2 1 2


PHYSICS






[Ans. 11.38 × 10–19 kg ]


[Ans. 6.25 sec ]











[Ans. T = 4r 21

0

qqmr

; V = mr4qq

0

21

]





[Ans.

312

Rmkqv

2

]


+q –4q

+4q –q

(1)

(3)

–q +4q

–4q q

(2)

(4)



-2q

+3q

-4q

+q

+Q-3q



(ii) Find AF



[Ans. (i) 7.2 N (ii) BF

= 7.2

j

54i

53

N ; AF

= 7.2

j

54i

53

N ]



MOLE CONCEPT –DPP-1

Subjective 1. Find out number of moles in 0.0036 gram of water?

2. Find out number of atoms in following a. 5 moles of oxygen b. 5 moles of water c. 5 moles of glucose d. 5 moles of CuSO4.5H2O

3. Find out number of atoms in following A. 25 moles of nitrogen B. 0.24 moles of methane C. 1.2 moles of glucose D. 200 milimoles of water Hint: 1 mole = 1000 millimoles

4. Convert following into moles A. 3.011 × 1023 molecules of water B. 1.2044 × 1025 molecules of water C. 3.011 × 1020 molecules of oxygen D. 2.4088 × 1022 molecules of nitrogen

5. Find out number of electrons in following A. 6.022 × 103 molecules of water B. 10 moles of water C. 0.0024 moles of carbon dioxide D. 400 milimoles of oxygen

6. What is mass of five sodium atoms in amu

7. What should be mass of one molecule of water in gram?

8. Find out mass of one Mg atom in gram

9. One atom of an element X weighs 6.644 × 10–23 g. Calculate the number of moles of X in 40 kg of it

10 4.6 × 1022 atoms of an element weigh 13.8 gm. The gram atomic mass of the element

is: (NA = 6 × 1023)

11. Find out number of moles of CH4 in 5.6 L of CH4 at STP.

12. Find out volume of 10 moles methane at STP.

Objective (Only one option is correct) 1. The mass of 3.2 ×105 atoms of an element is 8.0 ×10–18 g. the atomic mass of the

element is about (NA = 6×1023) 1. 2.5 ×10–22 2. 15 3. 8.0×10–18 4. 30 2. Number of electrons in 18 g H2O 1. 6.022 × 1022 2. 6.022 × 1023 3. 6.022 × 1024 4. 6.022 × 1025 3 The number of neutrons present in 9 mg of O18 is

1. 10 2. 5NA 3. 0.005 NA 4. 0.0005 NA


2 4. Which of the following have largest number of atoms?

1. 4 gm oxygen (at mass O = 16) 2. 16 gm sulphur (at mass S = 32) 3. 35.5 gm chlorine (at mass Cl = 35.5) 4. 14 gm lithium (at mass Li = 7) 5. Number of oxygen molecules having weight equal to weight of 20 molecules of SO3. 1. 100 2. 50 3. 15 4. 8 6. The weight of 3.2 × 105 atoms of an element is 8.0 × 10–18 gm. The atomic weight of

the element should be about 1. 2.5 × 10–22 2. 15 3. 1.5 4. 150

7. The number of molecules of water in 333 g of Al2(SO4)3. 18H2O is

1. 18.0 × 6.02 × 1023 2. 9.0 × 6.02 × 1023

3. 18.0 4. 36.0 8. The mass of 2 gram atoms of calcium (atomic mass = 40) 1. 2 g 2. 0.05 g 3. 0.5 g 4. 80 g 9. The number of molecules present in 88 g of CO2 (Relative molecular mass of

CO2 = 44) 1. 1.24 × 1023 2. 3.01 × 1023 3. 6.023 × 1024 4. 1.2046 ×1024

10. One a.m.u. is equivalent to 1. 1.66 × 10–24 kg 2. 1.66 × 10–25 kg 3. 1.66 × 10–26 kg 4. 1.66 × 10–27 kg 11. The number of atoms present in 0.05g of water is 1. 1.67 × 1023 2. 1.67 × 1022 3. 5.02 × 1021 4. 1.67 × 1021 12. How many moles of Magnesium phosphate Mg3(PO4)2 will contain 0.25 mole of

oxygen atoms? 1. 0.02 2. 3.125 × 10–2 3. 1.25 × 10–2 4. 2.5 × 10–2

13. Which has the maximum no. of atom? 1. 6 g C 2. 1 g H2 3, 12 g Mg 4. 30 g Ca

Answers – Mole concept –DPP-1 Subjective 1. [0.0002] 2. [(a ) 6.022 × 1024 (b) 9.033 × 1024 (c) 7.2264 × 1025 (d) 6.323 × 1025 3. [A. 25× 2 × NA B. 0.24 × 5 × NA C. 1.2× 24× NA D. 200× 10–3× 3× NA ] 4. [A. 0.5 B. 20 C. 5 × 10–4 D. 0.04] 5. [A. 6.022 × 104 B. 10 ×10 × 6.022 × 1023 C. 3.17 × 1022 D. 3.85 × 1024 ] 6. [115 amu] 7. [29.88 × 10-24 gram] 8. [39.84 × 10-24 gram] 9. [1000] 10. [180]11. [0.25] 12. [224]

Objective

Q. No. 1 2 3 4 5 6 7 8 9 10 Answer 2 3 3 4 2 2 2 4 4 4 Q. No. 11 12 13 Answer 3 2 2

PHYSICS


JRS TUTORIALSVECTOR (11th PMT)

DPP-011. A physical quantity which has a direction :

(A) cannot be a vector (B) must be a vector (C) must be a scalar (D) may be a vector

2. The magnitude of a vector cannot be :

(A) positive (B) unity (C) negative (D) zero

3. Which of the following vector is equal as that of 1 m

(A) 1 m (B) 2 m

(C) 1 m

(D) 1 m

4. The forces, each numerically equal to 5 N, are acting as shown in the Figure. Find the anglebetween forces?(A) 90°

(B) 120°

(C) 0°

(D) 60°

5. For the figure shown.

(A) A B C

(B) B C A

(C) C A B

(D) A B C 0

6. Six vectors, a through f

have the mangitudes and directions indicated in the figure.Which of

the following statements is true ?

`

(A) b + c = f

(B) d + c = f

(C) d + e = f

(D) b + e = f

PHYSICS


7. Column-I show vector diagram relating three vectors a, b and c . Match the vector equation in

column-II, with vector diagram in column-I and choose the correct option :

Column-I Column-II

(I)a

bc(P) 0)cb(a

(II)a

cb (Q) acb

(III)a b

c(R) cba

(IV)b

ca (S) cba

(A) (I)-R ; (II)-S ; (III)-Q ; (IV)-P (B) (I)-P ; (II)-R ; (III)-S ; (IV)-Q

(C) (I)-Q ; (II)-S ; (III)-P ; (IV)-R (D) (I)-R ; (II)-S ; (III)-P ; (IV)-Q

8. If the magnitude of velocity v is 2 2 ms–1. Then v is

(A) –1 –1ˆ ˆv (2 ms ) i + (2 ms ) j

(B) –1 –1ˆ ˆv (2 ms ) i – (2 ms ) j

45°

Y

X

vY'

X'

(C) –1 –1ˆ ˆv (2 ms ) i – (2 ms ) j

(D) –1 –1ˆ ˆv (2 ms ) i + (2 ms ) j

9. If the magnitude of a is 20 ms–2. Then a is

(A) –2 –2ˆ â (10 3 ms ) i + (10 ms ) j

(B) –2 –2ˆ â (10 ms ) i + (10 3 ms ) j 60°

Y

X

a

Y'

X'

(C) –2 –2ˆ â (10 ms ) i – (10 ms ) j

(D) –2 –2ˆ â (10 3 ms ) i + (10 ms ) j

PHYSICS


10. The magnitude of momentum p of a paticle is 40 N-s.The momentum p of the particle is

(A) ˆ ˆp (20 N-s) i (20 3 N-s) j

(B) ˆ ˆp (20 N-s) i (20 3 N-s) j

30°

Y

X

pY'

X'

(C) ˆ ˆp (20 3 N-s) i (20 N-s) j

(D) ˆ ˆp (20 3 N-s) i (20 N-s) j

11. A man moves 20 m in a direction 30° North of West. Represent displacement in the form of unit

vectors assuming east as positive X axis and north as positive Y axis.

(A) ˆ ˆs (10 m) i (10 3 m) j (B) ˆ ˆs ( 10 3 m) i (10 m) j

(C) ˆ ˆs (10 3 m) i (10 m) j (D) ˆ ˆs (10m) i (10 3 m) j

12. A man moves 10 m in a direction 30° East of North.The displacement of man is [assuming east

as positive X axis and north as positive Y axis]

(A) ˆ ˆs 5 3 i 5 j m

(B) ˆ ˆs 5i 5 3 j m

(C) ˆ ˆs 5 3i 5 j m

(D) ˆ ˆs 5 i 5 3 j m

13. A person pushes a box kept on a horizontal surface with force of 100 N. In unit vector notationforce F

can be expressed as :

(A) 100 ˆ ˆ(i j)

(B) 100 ˆ ˆ(i j)

45°

y

xF

(C) 250 ˆ ˆ(i j)

(D) 50 2 ˆ ˆ(i j)

14. Just after firing, a bullet is found to move at an angle of 37° to horizontal. Its acceleration is 10m/s2 downwards. Find the component of acceleration in the direction of the velocity.

(A) – 6 m/s2

(B) – 4 m/s2

(C) – 8 m/s2

(D) – 5 m/s2

15. A man walks 40 m North, then 30 m East and then 40 m South. What is his displacement fromthe starting point ?(A) 30 m East (B) 150 m West (C) 40 m West (D) 150 m East

16. A person moves 30 m North then 20 m East then 30 2 m South West. His displacement fromthe original position is(A) 15 m East (B) 28 m South (C) 10 m West (D) 14 m South-West

PHYSICS


17. A particle moves along a path ABCD as shown in the figure. Then the magnitude of netdisplacement of the particle from position A to D is :(A) 10 m

(B) 25 m(C) 9 m(D) 27 m

18. Find the resultant of three vectors OA

, OB

and OC

and each of magnitude R(A) 2R(B) R(1 + 2 )(D) R 2

(D) R( 2 – 1)

19. Find resultant force as vector in ˆ ˆai bj format.

(A) ˆ ˆ225 i 300 j

(B) ˆ ˆ475 i 900 j

(C) ˆ ˆ475 i 600 j

(D) ˆ ˆ475 i 900 j

20. Two horizontal forces of magnitudes 10 N & P N act on a particle. The force of magnitude 10 Nacts due west & the force of magnitude P N acts on a bearing of 30° east of north as shown infigure. The resultant of these two force acts due north. Find the magnitude of this resultant.(A) 310 N

(B) 20 N(C)10 N(D) 10 / 3 N

21. Three forces acting on a body are shown in the figure. To have the resultant force only along the

y-direction, the magnitude of the minimum additional force needed is:

(A) 0.5N (B) 1.5N (C) 3 N

4(D) 3N

PHYSICS


22. As shown in figure, find the magnitude of the unknown forces X and Y if sum of all forces iszero.(A) 5N, 5N(B) 5N, 10N(C) 10N, 5N(D) 10N, 10N

23. An insect crawls 10 m towards east, turns to its right, crawls 8 m, and again turns to its right,Now crawling a distance of 2 m it turns to its right and stop after moving 2 m more. Find its netdisplacement.(A) 10 m , 37° S of E (B) 10 m , 37° E of S(C) 5 m , 37° S of E (D) 5 m , 37° W of N

24. A sail boat sails 2 km due East, 5 km 37o South of East and finally an unknown displacement .If the final displacement of the boat from the starting point is 6 km due East, the third displace-ment is ______(A) 3 km North (B) 3 km South (C) 4 km South (D) 4 km East

ANSWER KEY

VECTOR DPP-01

1. D 2. C 3. C 4. B 5. C 6. C

7. D 8. C 9. B 10. B 11. B 12. D

13. C 14. A 15. A 16. C 17. D 18. B

19. D 20. A 21. A 22. B 23. A 24. A


PHYSICS






[Ans. 11.38 × 10–19 kg ]


[Ans. 6.25 sec ]











[Ans. T = 4r 21

0

qqmr

; V = mr4qq

0

21

]





[Ans.

312

Rmkqv

2

]


+q –4q

+4q –q

(1)

(3)

–q +4q

–4q q

(2)

(4)



-2q

+3q

-4q

+q

+Q-3q



(ii) Find AF



[Ans. (i) 7.2 N (ii) BF

= 7.2

j

54i

53

N ; AF

= 7.2

j

54i

53

N ]


PHYSICS


DPP-04 : Coulomb’s Law

1. Two point charges are located on the positive x-axis of a coordinate system (as shown in figure).Charge q1 = 1.0 nC is 2.0 cm from the origin, and charge q2 = 3.0 nC is 4.0 cm from the origin.What is the total force exerted by these two charges on a charge q3 = 5.0 nC located at the origin.Gravitational forces are negligible.(A) 28 N ( )

(B) 28 N ( )

3q

2q1q

Ocm0.2

cm0.4

)cm(x

(C) 196 N ( )

(D) 196 N ( )

2. Equal charges of each 2C are placed at a point x = 0, 2, 4, and 8 cm on the x-axis. The forceexperienced by the charge at x = 2 cm is equal to-

(A) 5 Newton (B) 10 Newton (C) 0 Newton (D) 15 Newton

3. In fig. two equal positive charges q1 = q2 = 2.0 C interact with a third point charge Q = 4.0 C.

Find the magnitude and direction of the net force on Q.

(A) 0.23 N ( )

(B) 0.46 N ( )

C0.2q2

C0.2q1

m50.0C0.4Q

x

m30.0

m30.0

(C) 0.23 N ( )

(D) 0.46 N ( )

4. Three charges –q1, +q2 and –q3 are placed as shown in figure. The x-component of the force on– q1 is proportional to – [AIEEE-2003]

(A) 22

bq

+ 23

aq

sin

(B) 22

bq

+ 23

aq

cos

(C) 22

bq

– 23

aq

sin

(D) 22

bq

– 23

aq

cos

5. ABC is a right angle triangle AB = 3cm, BC = 4cm charges 15, 12,20 esu are placedat A, B and C respectively. The magnitude of force experienced by charge at B in dyne is-(A) 125 dynes (B) 35 dynes (C) 25 dynes (D) 0


PHYSICS6. Three point charge +q, +q and –q are placed at the corners of an equilateral triangle of side ‘a’.

Another charge +Q is kept at the centroid. Force exerted on Q is

(A) 20

24

1aqQ

(B) 20

64

1aqQ

(C) 20

84

1aqQ

(D) 20

124

1aqQ

7. Four charges are arranged at the corners of a square ABCD, as shown. The force on a +vecharge kept at the centre of the square is(A) zero(B) along diagonal AC(C) along diagonal BD

+qB C

DA–2q +2q

–q

(D) perpendicular to the side AB8. Four charges are placed at the circumference of a dial clock as shown in figure. If the clock has

only hour hand, then the resultant force on a charge q0 placed at the centre, points in the directionwhich shows the time as :–

(A) 1:30

(B) 7:30 +q

+q

q

q

q0

39

12

6(C) 4:30

(D) 10:30

9. Six charges are placed at the corner of a regular hexagon as shown. If an electron is placed at itscentre O, force on it will be:(A) Zero(B) Along OF (C) Along OC(D) None of these

10. In Fig. the magnitude of force experienced by Q at centre O is

(A) 20

21a

qQ (B) 2

041

aqQ

A B

CD

q 2q

3q4q

O

(C) 20

24

1a

qQ (D) 2

0

1aqQ

11. Four positive charges (22-1) Q are arranged at corner of a square. Another charge q is

placed at the centre of the square. Resultant force acting on each corner is zero If q is(A) – 7Q/4 (B) – 4Q/7 (C) -Q (D) 7Q/4

12. Four charges, each with charge +q, are placed at the four corners of a square of side , which

contains a charge 4q at its centre. The net force on any one corner of the square is :

(A) 2

2

0

q4

1

(B) 2

2

0

q24

1

(C) zero (D) 2

2

0

q224

1


PHYSICS13. In the basic CsCl crystal structure, Cs+ and Cl– ions are arranged in a bcc configuration

as shown in fig.The net electrostatic force exerted by the eight Cs+ ions on the Cl– ion is

(A) 2

2

0 a3e4

41

(B) 2

2

0 a3e16

41

Cs+Cs+

Cs+Cs+

Cs+

Cs+

Cs+Cs+

Cl–a

a(C)

041 2

2

a3e32

(D) zero

14. Four point +ve charges of same magnitude (Q) are placed at four corners of a rigid square frame

as shown in figure. The plane of the frame is perpendicular to Z axis. If a –ve point charge is

placed at a distance z away from the above frame (z << L) then(A) –ve charge oscillates along the Z axis(B) It moves away from the frame

Q Q

QQ

. L

Z-axis(C) It moves slowly towards the frame and stays in the plane of the frame(D) It passes through the frame only once

15. Five point charges, each of value + q, are placed on five vertices of a regular hexagon ofside L. The magnitude of the force on a point charge of value – q placed at the centre ofthe hexagon is

(A) 2

2

LKq (B) 2

2

L4Kq (C) 2

2

L2Kq (D) 2

2

L8Kq

16. Fig. shows a fixed charge Q and a movable charge –q. The latter is free to move only along

the vertical direction. The charge –q is in equilibrium, because its weight is balanced by the

electrostatic attraction. In which of the cases shown in fig. the charge –q is in equilibrium?

The separation between the charges remains unchanged.

• + Q

• – q

(A)

• – q

• + Q (B)

• – Q

• – q (C)

• + q

• – Q (D)

• – q

• – Q


PHYSICS17. Three equal and similar charges are placed at (–a, 0, 0), (0, 0, 0) and (+a, 0, 0). What is the nature

of equilibrium of the charge at the origin-(A) Stable when moved along the Y-axis (B) Stable when moved along Z-axis(C) Stable when moved along X-axis (D) Unstable in all of the above cases

18. Three point charges are placed at the corners of an equilateral triangle. Assuming only electrostaticforces are acting,(A) the system can never be in equilibrium(B) the system will be in equilibrium if the charges rotate about the centre of the triangle(C) the system will be in equilibrium if the charges have different magnitudes and different signs(D) the system will be in equilibrium if the charges have the same magnitude but different signs.

19. Two equal negative charges – q, are placed at points (0,a) and (0,–a) on y axis, one positivecharge q at rest is left to move from point (2a, 0). This charge will be(A) execute S.H.M. about the origin.(B) oscillate but not execute S. H. M.(C) move towards origin and will become stationary.(D) S. H. M. along x axis.

20. When two charges are placed at some distance apart find the magnitude of third charge which is

placed at mid point the line joining the charges so that system is in equilibrium [AIEEE-2002]

(A) Q4

(B) Q2

(C) Q3

(D) – Q

21. A charge q is placed at the centroid of an equilateral triangle. Three equal charges Q are placedat the vertices of the triangle. The system of four charges will be in equilibrium if q is

(A) 3Q

(B) 3Q

(C) 3Q (D) 3Q

22. Four charges equal to – Q are placed at the four corners of a square and a charge q is at its centre.If the system is in equilibrium the value of q is [AIEEE-2004]

(A) –4Q (1 + 2 2 ) (B)

4Q (1 + 2 2 ) (C) –

2Q (1 + 2 2 ) (D)

2Q (1 + 2 2 )

23. If a charge q is placed at the centre of the line joining two equal charges – Q each such that thesystem is in equilibrium, then the minimum possible value of q is :(A) e (B) 2e (C) 4e (D) 3e

24. A charged particle q1 is at position (2, 1, 3). The electrostatic force on another charged particle

q2 at (0, 0, 0) is :

(A) 0

21

56qq )k3ji2( (B)

0

21

1456qq

)k3ji2(

(C) 0

21

56qq )k3i2j( (D)

0

21

1456qq

)k3i2j(


PHYSICS25. Two positive ions, each carrying a charge q, are separated by a distance d. If F is the force of

repulsion between the ions, the number of electrons missing from each ion will be (e being thecharge on an electron): [AIPMT-2010]

(A) 2

02

4 Fd

q(B)

202

4 Fd

e(C)

202

4 Fe

d(D)

202

4 Fd

e

26. Two identical charged spheres suspended from a common point by two mass less strings oflength , are initially at a distance d(d ) a part because of their mutual respulsion. Thecharges begin to leak from both the spheres at a constant rate, the spheres approach each otherwith a velocity v. Then v varies as a function of the distance x between the spheres, as :

[NEET-2016](A) 1v x (B) 1/2v x (C) v x (D) 1/2v x

27. Suppose the charge of a proton and an electron differ slightly. One of them is – e, the other is(e e). If the net of electrostatic force and gravitational force between two hydrogen atomsplaced at a distance d (much greater than atomic size) apart is zero, then e is the order of[ Given mass of hydrogen mh = 1.67×10–27 kg] [NEET-2017](A) 10–23C (B) 10–37C (C) 10–47C (D) 10–20C

ANSWER KEYELECTROSTATICS DPP-04

1. A 2. B 3. B 4. A 5. C 6. B

7. D 8. B 9. D 10. A 11. A 12. B

13. D 14. A 15. A 16. D 17. C 18. A

19. B 20. A 21. A 22. B 23. C 24. D

25. D 26. D 27. B

PHYSICS



DPP-05 : ELECTRIC FIELD1. Figure shows a metal body of mass M charged positively. P is a point in front of the body. The

electric field at point P due to the body M is Ep. Now a negative change –q is placed at point Pand it experiences a force F. then(A) Ep = F/q

(B) Ep < F/q(C) Ep > F/q

(D) None of these.2. Two charges 9e and 3e are placed at a distance r. The distance of the point where the

electric field intensity will be zero is:

(A)

31r

from 9e charge (B)

3/11r

from 9e charge

(C)

31r

from 3e charge (D)

3/11r

from 3e charge.

3. Two point charges +8q and –2q are located at x = 0 and x = L respectively. The location of apoint on the x axis at which the net electric field due to these two point charges is zero is

(A) 2 L (B) L/4 (C) 8 L (D) 4 L4. Charges 2Q and –Q are placed as shown in figure. The point at which electric field intensity is

zero will be:(A) Somewhere between –Q and 2Q(B) Somewhere on the left of –Q(C) Somewhere on the right of 2Q(D) Somewhere on the right bisector of line joining –Q and 2Q

5. Three charge particles +2q (a,0), +q (0,a) and q (0, a) are placed on the circumference of acircle of radius ‘a’ and centre at origin . The electric field at the centre ‘O’ of the circle will be

(A) 20a4q2

(B) 20a4q2

(C) 20a4

q22 (D) 2

0a4q

6. Four point charges are placed at the corners of a square with diagonal 2a as shown. What is the

total electric field at the center of the square?

(A) kq/a2 at an angle 45° above the +x axis

(B) kq/a2 at an angle 45° below the –x axis

(C) 9kq/a2 at an angle 45° above the +x axis

(D) 3kq/a2 at an angle 45° below the +x axis

PHYSICS


7. Four electrical charges are arranged on the corners of a 10 cm square as shown.What would be the

direction of the resulting electric field at the center point P?

(A) (B)

(C) (D)

8. Four charges are placed on the circumference of a circle of radius R, 90° apart as shown in thefig. The electric field strength at the centre of the circle is

(A) 20 R

Q524

1 , making angle tan–12 with the – ve x-axis.

(B) 20 R

Q524

1 , making angle tan–12 with the + ve y-axis.

(C) 20 R

Q244


21

with the – ve x-axis.

(D) 20 R

Q244


21

with the + ve y-axis.

9. Figures below show regular hexagons, with charges at the vertices. In which of the followingcases the electric field at the centre is not zero

(1) (2)

q q

q

qq

q

q –q

q

–q

q

q(3) (4)

2q 2q

qq

2q q

2q

q

q

2q 2q 2q

(A) 4 (B) 3 (C) 2 (D) 110. Two charged particles (-q) and (-2q) are placed at the origin A and B of an isosceles right angle

triangle AOB, as shown in figure. The value of charge Q placed at the point P for which theelectric field at ‘O’ will be zero is,(A) Q = 3q/2(B) Q = 2q/3

A P

B O a

a

–q

–2q(C) Q = 3q

(D) Not possible11. Four point charges q, q, Q and 2Q are placed in order at the corners A, B, C and D of a

square. If the field at the midpoint of CD is zero then the value of Qq

is

(A) 1 (B) 25

(C) 5

22(D)

255

PHYSICS


12. Figures shows four situations in which charged particles are at equal distances from the origin.If E1, E2, E3 and E4 be the magnitude of the net electric fields at the origin in four situations (i),(ii), (iii) and (iv) respectively, then -

(i)

–5q

2q –3q

y

xO (ii)

–5q

3q –2q

y

xO (iii)

4q –q

y

xO

5q

(iv)

q –4q

y

x O

4q

–q

(A) E1 = E2 = E3 = E4 (B) E1 = E2 > E3 > E4 (C) E1 < E2 < E3 = E4 (D) E1 > E2 = E3 < E4

13. Charges q, 2q, 4q, 8q, ..... are placed along x-axis at r, 2r, 4r, 8r, ..... from origin respectively.The net electric field at origin is

(A) Infinite (B) 20

q4 r (C) 2

0

q2 r (D) 2

0

q8 r

14. A regular polygon has n sides each of length l. Each corner of the polygon is at a distance r

from the centre. Identical charges each equal to q are placed at (n – 1) corners of the polygon.

What is the electric field at the centre of the polygon

(A) 204 r

qn (B) 2

04 lqn

(C) 204

1rq

(D) 204

1lq

15. A point charge 50C is located in the x-y plane at the position vector m)j3i2(r0 . The

electric field (in N/C) at the point of position vector m)j5i8(r , in vector from is equal to

(A) 90 )j4i3( (B) 90 )j4i3( (C) 900 )j4i3( (D) 900 )j4i3(

16. The variation of electric field between the two charges q1 and q2 along the line joining thecharges is plotted against distance from q1 (taking rightward direction of electric field as positive)as shown in the figure. Then

(A) q1 and q2 are positive and q1 < q2

(B) q1 and q2 are positive and q1 > q2 q1 q2r

E

(C) q1 is positive and q2 is negative and q1 < q2

(D) q1 and q2 are negative and q1 < q2

17. A ring of radius R is charged uniformly with a charge + Q . The electric field at any point onits axis at a distance r from the circumference of the ring will be:–

(A) 2 2 3/2

KQr

(R r ) (B) 2

KQ

r(C) 1 / 22 2

3

KQr R

r (D) 3

KQr

R

18. A ring of radius R, has charge –Q distributed uniformly over it. A charge q is placed at the centreof the ring such that the electric field becomes zero at a point on the axis of the ring distant ‘R’from the centre of the ring. The value of charge q is

(A) Q 32

(B) Q 24

(C) Q 23

(D) Q 34

PHYSICS


ANSWER KEY

1. B 2. B 3. A 4. B 5. C 6. B

7. B 8. A 9. C 10. D 11. D 12. A

13. C 14. C 15. D 16. A 17. C 18. B




Subjective 1. A solid contains A+ and B¯ ions. The structure of solid is fcc for B¯ ions and A+ ions are

present in one fourth of tetrahedral voids as well as in one fourth of octahedral voids. What is the simplest formula of solid ?

2. A cubic solid is made by atoms A forming close pack arrangement, B occupying one.

Fourth of tetrahedral void and C occupying half of the octahedral voids. What is the formula of compound

3. Spinel is a important class of oxides consisting of two types of metal ions with the oxide

ions arranged in CCP pattern. The normal spinel has one-eight of the tetrahedral holes occupied by one type of metal ion and one half of the octahedral hole occupied by another type of metal ion. Such a spinel is formed by Zn2+, Al3+ and O2–, with Zn2+ in the tetrahedral holes. Give the formulae of spinel

4. A closed packed structure of uniform spheres has the edge length of 534 pm. Calculate

the radius of sphere, if it exist in (a) simple cubic lattice (b) BCC lattice (c) FCC lattice

5. An element crystallizes into a structure which may be described by a cubic type of unit cell having one atom on each corner of the cube and two atoms on one of its body diagonals. If the volume of this unit cell is 24×10–24 cm3 and density of element is 7.2 g cm–3, calculate the number of atoms present in 200 g of element.

6. A cubic unit cell contains manganese ions at the corners and fluoride ions at the center of each edge. (a) What is the empirical formula of the compound? (b) What is the co-ordination number of the Mn ion? 7. An element (atomic mass = 100) having BCC structure has unit cell edge length 400

pm. The density of this element will be (NA = 6 × 1023) 8. A solid has three types of atoms X, Y and Z. ‘X’ forms a FCC lattice with ‘Y’ atoms

occupying all the tetrahedral voids and ‘Z’ atoms occupying half the octahedral voids. The simplest formula of solid is

9. Lithium metal crystallizes in a body-centred cubic crystal. If the length of the side of the

unit cell of lithium is 351 pm, the atomic radius of lithium will be 10. A crystalline solid of a pure substance has a face-centred cubic structure with a cell edge

of 400 pm. If the density of the substance in the crystal is 8 g cm–3, Calculate the number of atoms present in 256 g of the crystal :


Page-2

Only one option is correct 1. Copper crystallizes in a face-centred cubic lattice with a unit cell length of 361 pm.

What is the radius of copper atom in pm? 1. 157 2. 181 3. 108 4. 128 2. If the radius of the anion in an ionic solid is 200 pm, what would be the radius of the

cation that fits exactly into a cubic hole 1. 146.4 pm 2. 82.8 pm 3. 45 pm 4. 60.8pm

3. The decreasing order of size of the void is 1. cubic > octahedral > tetrahedral > Trigonal 2. trigonal > tetrahedral > octahedral > cubic 3. Trigonal > octahedral > tetrahderal > cubic 4. cubic > tetrahedral > octahedral > trigonal 4. For the structure given below the site marked as S is a 1. Tetrahedral void 2. Cubic void 3. Octahedral void 4. None of these 5. If a stands for the edge length of the cubic system: simple cubic, body centred cubic and

face centred cubic, then the ratio of radii of the spheres in these systems will be respectively

1. a22:a

23:a

21 2. 1a : a3 : a2

3. a22

1:a43:a

21 4. aaa

21:3:

21

6. In which of the following substances the carbon atom is arranged in a regular tetrahedral structure. 1. Diamond 2. Benzene 3. Graphite 4. Carbon black 7. For a solid with the following structure, the co-ordination number

of the point B is 1. 3 2. 4 3. 5 4. 6 8. In a hexagonal close packed (hcp) structure of spheres, the fraction of the volume occupied by the sphere is A. In a cubic close packed structure, the fraction is B. The relation for A and B is 1. A = B 2. A < B 3. A > B 4. A is equal to the fraction in a simple cubic lattice. 9. In a close packed array of N spheres, the number of tetrahedral holes are 1. 2/N 2. 4N 3. 2N 4. N

S

A B


Page-310. If the radius ratio is in the range of 0.225–0.414, then the coordination number

will be 1. 2 2. 4 3. 6 4. 8

11. In a solid C atom are forming CCP lattice with A atoms

occupying all tetrahedral voids and B atoms occupying all octahedral voids. Which of the following arrangement is obtained along the plane shown in diagram?

1. 2. 3. 4.

19. A metallic crystal crystallizes into a lattice containing a sequence of layers AB AB

AB....Any packing of spheres leaves out voids in the lattice. What percentage of volume of this lattice is empty space, 1. 74% 2. 26% 3. 50% 4. 40%

13. The fraction of octahedral voids filled by Al3+ ions in Al2O3 )43.0/( 23 =−+ OAl

rr is 1. 0.43 2. 0.287 3. 0.667 4. 1

14. Which of the following expressions is correct for an NaCl unit cell with lattice parameter a

1. 2a

rr ClNa =+ −+ 2. −+ + ClNa rr = 4a

3. 4a

r ClNa r =+ −+ 4. a43

rr ClNa =+ −+

15. In a unit cell atoms (A) are present at all corners atom(B) are present at 50% faces and all edge centre, Atoms(C) are present at face centres left from (B) and 1 at each body diagonal at distance of 1/4 th of body diagonal from corner. Formula of the given solid is

1. A3B8C7 2. AB4C6 3. A6B4C8 4. A2B9C11

16. Which of the following statements is correct for 3CsBr 1. It is a covalent compound

2. It contains +3Cs and −Br ions 3. It contains +Cs and −

3Br ions. 4. It contains +Cs , −Br and lattice 2Br molecule

17. A crystal is made of particles X and Y. X forms fcc packing and Y occupies all the

octahedral voids. If all the particles along one body diagonal are removed then the formula of the crystal would be

1. X4Y3 2. X5Y4 3. X4Y5 4. X3Y4

CCP unit cell

C C

C C

B

B

B B A

B A

C C C

C C C

B B B

C C C

C C C

B B B A A A A

C C C

C C C

B B B


Page-4

18. In a face centred cubic arrangement of A and B atoms when A atoms are at the corner of the unit cell and B atoms of the face centres. One of the A atom is missing from one corner in unit cell. The simplest formula of compound is

1. 37BA 2. 3AB 3. 247BA 4. 38/7 BA

19. Ferrous oxide has a cubic structure and each edge of the unit cell is 5.0 Å. Assuming density of the oxide as 4.0 g 3cm−− , then the number of +2Fe and −2O ions present in each unit cell will be 1. Four +2Fe and four −2O 2. Two +2Fe and four −2O 3. Four +2Fe and two −2O 4. Three +2Fe and three −2O

20. For an octahedral arrangement the lowest radius ratio limit is 1. 0.155 2. 0.732 3. 0.414 4. 0.225

Answer DPP-3

Subjective 1. [A3 B4] 2. [A4B2C2] 3. [ZnAl2O4] 4. [ 267pm , 231.2pm ,188.8pm

5. [3.472 × 1024 atoms] 6. [ (a) MnF3 (b) 6 ] 7. [5.2 g/ml]

8. [X2Y4Z] 9. [151.8 pm] 10. [2 × 1024]

Only one option is correct

Q.No. 1 2 3 4 5 6 7 8 9 10 Ans 4 1 1 3 3 1 4 1 3 2

Q.No. 11 12 13 14 15 16 17 18 19 20 Ans 3 3 3 1 4 3 2 3 1 3




Subjective 1. Cesium chloride forms a body centered cubic lattice. Cesium and chloride ions are in

contact along the body diagonal of the unit cell. The length of the side of the unit cell is 412 pm and Cl– ion has a radius of 181 pm. Calculate the radius of Cs+ ion.

2. If the radius of Mg2+ ion, Cs+ ion, O2– ion, S2– ion and Cl– ion are 0.65 Å , 1.69 Å, 1.40

Å, 1.84 Å, and 1.81 Å respectively. Calculate the co-ordination numbers of the cations in the crystals of MgS, MgO and CsCl.

3. KCl crystallizes in the same type of lattice as does NaCl. Given that 5.0=−

+

Cl

Na

rr

and

7.0=+

+

K

Na

rr

Calculate:

(a) The ratio of the sides of unit cell for KCl to that for NaCl and (b) The ratio of densities of NaCl to that for KCl. 4. A unit cell of sodium chloride has four formula units. The edge of length of the unit

cell is 0.564 nm. What is the density of sodium chloride. 5. In a cubic crystal of CsCl (density = 3.97 gm/cm3) the eight corners are occupied by Cl–

ions with Cs+ ions at the centre. Calculate the distance between the neighbouring Cs+ and Cl– ions.

6. An ionic compound AB has ZnS type structure. if the radius A+ is 22.5 pm, then

calculate the ideal radius of B- would be 7. KF has NaCl structure. What is the distance between K+ and F– in KF if density of KF is

2.48 gm/cm3. 8. NaH crystallizes in the same structure as that of NaCl. The edge length of the cubic unit

cell of NaH is 4.88 Å. (a) Calculate the ionic radius of H–, provided the ionic radius of Na+ is 0.95 Å. (b) Calculate the density of NaH.

9. AgCl has the same structure as that of NaCl. The edge length of unit cell of AgCl is

found to be 555 pm and the density of AgCl is 5.561 g cm–3. Find the percentage of sites that are unoccupied.

10 A crystal of lead(II) sulphide has NaCl structure. In this crystal the shortest distance

between Pb+2 ion and S2– ion is 297 pm. What is the length of the edge of the unit cell in lead sulphide? Also calculate the unit cell volume.


Page-2

Only one option is correct 1. A binary solid (AB) has a rock salt structure. If the edge length is 400 pm, and radius of

cation is 80 pm the radius of anion is 1. 100 pm 2. 120 pm 3. 250 pm 4. 325 pm 2. In which case, can we see 12 as coordination number : 1. ZnS 2. CaF2 3. NaCl 4. Ag 3. In CsCl structure, the coordination number of +Cs is 1. Equal to that of −Cl , that is 6 2. Equal to that of −Cl , that is 8 3. Not equal to that of −Cl , that is 6 4. Not equal to that of −Cl , that is 8 4. Which of the following statement (s) is incorrect

1. The coordination number of each type of ion in CsCl crystal is 8 2. A metal that crystallizes in bcc structure has a coordination number of 12 3. A unit cell of an ionic crystal shares some of its ions with other unit cells. 4. The adge length of the unit cell in NaCl is 552 pm ( +Na

r = 95 pm; −Clr = 181 pm)

5. If the radius of Cs+ = 1.69 Å and Br- = 1.95 Å, then which of the following is correct

statement? 1. Edge length of until cell is 8.2 Å 2. Coordination number of Cs+ is 6 3. CsBr has BCC type structure 4. Br– ions touch each other along the edge 6. RbCl has NaCl type lattice and its unit cell length is 0.30 Å greater than that for KCl.

If +Kr = 1.33 Å , the ionic radius of Rb+ is

1. 1.48 Å 2. 1.63 Å 3. 1.03 Å 4. 1.75Å 7. 8 : 8 co-ordination is noticed in – 1. MgO 2. Al2O3 3. CsCl 4. All 8. A certain sample of cuprous sulphide is found to have composition Cu1.8S, because of

incorporation of Cu2+ ions in the lattice. What is the mole % of Cu2+ in total copper content in this crystal?

1. 99.8% 2. 11.11% 3. 88.88% 4. 94% 9. A solid +A −B has a body centred cubic structure. The distance of closest approach between the two ions is 0.767 Å. The edge length of the unit cell is

1. 23 pm 2. 142 = 2 pm 3. 2 pm 4. 81.63 pm.

10. For an ionic crystal of the general formula AX and co-ordination number 6, the radius ratio value will be, 1. greater than 0.73 2. between 0.73 and 0.41

3. between 0.41 and 0.22 4. less than 0.22 11. NH4Cl crystallizes in a body-centered cubic type lattice with a unit cell edge length of

387 pm. The distance between the oppositively charged ions in the lattice is 1. 335.1 pm 2. 83.77 pm 3. 274.46 pm 4. 137.23 pm 12. If the distance between Na+ and Cl– lons in NaCl crystal is 'a' pm, what is the length of

the cell edge? 1. 2a pm 2. a/2 pm 3. 4a pm 4. a/4 pm


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13. Which statement is correct in antifluorite structure of Na2O 1. O2– ions have CCP arrangement 2. It has 4 :8 coordination 3. Na+ ions occupy all the tetrahedral sites 4. All are correct 14. The number of nearest neighbours and next nearest neighbours of a Na+ ion in a crystal

of NaCl are respectively : 1. 6Na+, 12Cl– 2. 6Cl–, 12Na+ 3. 12Cl–, 6Na+ 4. 6Cl–, 6Na+ 15. In solid CsCl each Cl– is closely packed with how many Cs+ 1. 8 2. 6 3. 10 4. 2 16. For an ionic crystal of the general formula AX and coordination number 6, the value of radius ratio will be 1. Greater than 0.73 2. In between 0.73 and 0.41 3. In between 0.41 and 0.22 4. Less than 0.22. 17. Which of the following statements is correct in the zinc-blende type structure of an ionic

compound? 1. Coordination number of each cation and anion is two 2. Coordinate number of each cation and anion is four 3. Coordination number of each cation and anion is six 4. Coordination number of each cation and anion is eight 18. Select the incorrect statement 1. CsCl changes to NaCl structure on heating 2. NaCl changes to CsCl structure on applying pressure 3. Coordination number increases on applying pressure

4. Coordination number increases on heating

19. CsBr has bcc type structure with edge length 4.3 pm. The shortest inter ionic distance in between Cs+ and Br– is

1. 3.72 pm 2. 1.86 pm 3. 7.44 pm 4. 4.3 pm

20. In a solid ‘AB’ having the NaCl structure, ‘A’ atoms occupy the corners of the cubic unit cell. If all the face centered atoms along one of the axes are removed, then the resultant stoichiometry of the solid is :

1. AB2 2. A2B 3. A4B3 4. A3B4

Answer –DPP-4

Subjective

1. [175.8 pm] 2. [4, 6, 8] 3. [(a) 1.143, (b) 1.172] 4. [2.16 gm/cm3]

5. [3.57 Å] 6. [100pm] 7. [2.685 Å] 8. [(a) 1.49 Å, (b) 1.37 g/cm3] 9. [0.24%]

10. [a =5.94 ×10–8 cm, V=2.096×10–22 cm–3]

Only one option is correct

Q.No. 1 2 3 4 5 6 7 8 9 10 Ans 2 4 2 2 3 1 3 2 4 2

Q.No. 11 12 13 14 15 16 17 18 19 20 Ans 1 1 4 2 1 2 2 4 1 4

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