2022Flame Institute

8. When strain is produced in a body within elastic limit, its internal energy

(a) Remains constant (b) Decreases (c) Increases (d) None of the above Answer-c (13)

11. Assertion : The Crystal structure gets stabilized even though the sum of elecron gain enthalpy and ionization enthalpy is positive . Reason : Energy is absorbed during the formation of crystal lattice.

a. If both assertion and reason are true and the reason is the correct explanation of the assertion b. If both assertion and reason are true but reason is not the correct explanation of the assertion c. If assertion is …

7. If the tension on a wire is removed at once, then

(a) It will break (b) Its temperature will reduce (c) There will be no change in its temperature (d) Its temperature increases Answer-d (12)

6. If the force constant of a wire is K, the work done in increasing the length of the wire by l is

(a) Kl/2 (b) Kl (c) Kl2 /2 …

5. A 5 metre long wire is fixed to the ceiling. A weight of 10 kg is hung at the lower end and is 1 metre above the floor. The wire was elongated by 1 mm. The energy stored in the wire due to stretching is

(a) Zero (b) 0.05 joule (c) 100 joule (d) 500 joule Answer-b (16)

10. Assertion : Graphite is an example of tetragonal crystal system. Reason : For a tetragonal system.

a = b ≠c, α = β = 90 °, ϒ = 120 ° a. If both assertion and reason are true and the reason is the correct explanation of the assertion b. If both assertion and reason are …

4. Two wires of same diameter of the same material having the length l and 2l. If the force F is applied on each, the ratio of the work done in the two wires will be

(a) 1 : 2 (b) 1 : 4 (c) 2 : 1 (d) 1 : 1 Answer-a (19)

3. Calculate the work done, if a wire is loaded by ‘Mg’ weight and the increase in length is ‘l’

(a) Mgl (b) Zero (c) Mgl/2 …

9. Assertion : No compound has both schottky and Frenkel defects. Reason : Both defects change the density of the solid.

2. The work done in stretching an elastic wire per unit volume is or strain energy in a stretched string is

(a) Stress × Strain (b) (1/2)(Stress× Strain) (c) 2× Stress × Strain (d) Stress/Strain Answer-b (8)

8. Assertion : Lead zirconate is a piezoelectric crystal. Reason : Lead zirconate crystals have no dipole moment.

1. If the potential energy of a spring is V on stretching it by 2 cm, then its potential energy when it is stretched by 10 cm will be

(a) V/25 (b) 5V (c) V/5 (d) 25V Answer-d (4)

7. Assertion : On heating ferromagnetic or ferrimagnetic substances, they become paramagnetic. Reason : The electrons change their spin on heating.

3. Assertion : Crystalline solids have short range order. Reason : Amorphous solids have long range order

2. Assertion : In crystal lattice the size of the cation is larger in a tetrahedral hole than in an octahdral hole. Reason : The cations occupy more space than anions in crystal packing.

1. Assertion : Diamond is a precious stone. Reason : Carbon atoms are tetrahedrally arranged in diamond

37. The statement that is INCORRECT about the interstitial compounds is

a. They are chemically reactive b. They have metallic conductive c. They are very hard d. They have high melting points Ans. a Explanation : Interstitial compound are almost inert so (a) is wrong statement (8)

36. The one that is extensively used as a piezoelectric material is :

a. Tridymite b. Amorphous silica c. Quartz d. Mica Ans. c Explanation : piezoelectric material are those that produce an electric current when they are placed under mechanical strees. (4)

34. Which type of ‘defect’ has the presence of cations in the interstitial sites

a. Frenkel defect b. Metal deficiency defect c. Schottky defect d. Vacancy defect Ans. a Explanation : frenkel defect (10)

33. Schottky defect in a crystal arises due to

a. Creation of equal number of cation and anion vacancies b. Creation of unequal number of cation and anion vacancies c. Migration of cations to interstitial voids d. Migration of anions to interstitial voids Ans. a Explanation : In schottky …

56. A solid sphere rolls down an inclined plane and its velocity at the

A solid sphere rolls down an inclined plane and its velocity at the bottom is v1. Then same sphere slides down the plane (without friction) and let its velocity at the bottom be v2. Which of the following relation is …

32. Experimentally it was found that a metal oxide has formula

M0.98 O. Metal M, present as M and M+2 in its oxide. Fraction of the metal which exists as M +3 would be a. 7.01% b. 4.08% c. 6.05 % d. 5. 08% Ans. b (32)

31. The defect that is more likely to occur in almost all types of ionic crystals is

a. Non- stoichiometric defects b. Shottky defects c. Frenkel defects d. all the above Ans. b (28)

55. A solid sphere of mass 0.1kg and radius 2cm rolls down an inclined plane 1.4m in length (slope 1 in 10). Starting from rest its final velocity will be

(a) 1.4 m/sec (b) 0.14 m/sec (c) 14 m/sec (d) 0.7 m/sec Ans .a (26)

54. A solid sphere and a disc of same mass and radius starts rolling down a rough inclined plane, from the same height the ratio of the time taken in the two cases is

(a) 15 : 14 (b) √15:√14 (c) 14 : 15 (d) √14:√15 Ans. d (6)

If NaCl si dopd with

10-4 mol % of SrCl2 the concentration of cation vacancies will be a. 6.02 x 1015 mol -1 b. 6.02 x 1016 mol -1 c. 6.02 x 1017 mol -1 d. 6.02 x 1014 mol -1 Ans. c (7)

53. A thin uniform circular ring is rolling down an inclined plane of in

A thin uniform circular ring is rolling down an inclined plane of inclination 30° without slipping. Its linear acceleration along the inclined plane will be (a) g/2 (b) g/3 (c) g/4 (d) 2g/3 Ans. c (8)

52. A ring solid sphere and a disc are rolling down from the top of the same height, then the sequence to reach on surface is

(a) Ring, disc, sphere (b) Sphere, disc, ring (c) Disc, ring, sphere (d) Sphere, ring, disc Ans. b (16)

51. A sphere rolls down on an inclined plane of inclination θ. What is the acceleration as the sphere reaches bottom

(a) 5/7 g sin θ (b) 3/5 g sin θ (c) 2/7 g sin θ (d) 2/5 g sin θ Ans. a (6)

50. A solid cylinder of mass M and radius R rolls without slipping down an inclined plane of length L and height h. What is the speed of its centre of mass when the cylinder reaches its bottom

(a) √(3/4) gh (b) √(4/3)gh (c) √4gh (d) √2gh Ans. b (19)

43. A body of moment of inertia

A body of moment of inertia of 3 kg-m2 rotating with an angular velocity of 2 rad/sec has the same kinetic energy as a mass of 12 kg moving with a velocity of (a) 8 m/s (b) 0.5 m/s (c) …

With which one of the following elements silicon should be doped so as to give p type of semicondutor

a. Selenium b. Boron c. Germanium d. Arsenic Ans. b Explanation : Boron can easily form positive ion. When silicon is doped with boron, it creates a positive hole and the substance are called p type semicondutor. (5)

14. The upper end of a wire of radius 4 mm and length 100 cm is clamped and its other end is twisted through an angle of 30°. Then angle of shear is

(a) 12° (b) 0.12° (c) 1.2° …

42. An automobile engine develops 100 kW when rotating at a speed of 1800 rev/min. What torque does it deliver

(a) 350 N-m (b) 440 N-m (c) 531 N-m (d) 628 N-m Ans. c (14)

13. The lower surface of a cube is fixed. On its upper surface, force is applied at an angle of 30° from its surface. The change will be of the type

(a) Shape (b) Size (c) None (d) Shape and size Answer-d (60)

Some of the polar crystal when heated produce electric current. This phenomena is termed as

a. Ferroelectric effect b. Pyrelectric effect c. Antiferroelectric effect d. piezoelectric effect Ans. b Explanation : pyroelectircity : It is the electricity produced when some polar crystals are heated (6)