2022Flame Institute

37.The ratio of diameters of two wires of same material is n : 1. The length of wires are 4 m each. On applying the same load, the increase in length of thin wire will be

(a) n2 times (b) n times (c) 2n times (d) None of the above Answer-a (10)

Which of the following polymer is used in pigment

a. Buna – S b. Neoprene c.Teflon d. Orlon Ans. a (11)

41. Two identical wires of rubber and iron are stretched by the same weight, then the number of atoms in the iron wire will be

(a) Equal to that of rubber (b) Less than that of the rubber (c) More than that of the rubber (d) None of the above Answer-c (7)

Biodegradable polymer which can be

a. PHBV b. Buna- N c. Nylon 6, 6 d. Nylon 2- nylon 6 Ans. d (6)

146.Two uniform similar discs roll down two inclined planes of length S and 2S respectively as shown is the fig. The velocities of two discs at the points A and B of the inclined planes are related as

(a) v1 = v2 (b) v1 =2v2 (c) v1 = v1 (v2/4) (d) v1 =( 3/4) v2 Ans. a (59)

which of the following is a biodegradable polymer

a. Cellulose b. Polythene c. Polyvinyl chloride d. Nylon -6 Ans. a (12)

The escape velocity for the earth is 11.2 km/sec. The mass of another planet is 100 times that of the earth and its radius is 4 times that of the earth. The escape velocity for this planet will be

(a) 112.0 km/s (b) 5.6 km/ (c) 280.0 km/s (d) 56.0 km/s Answer: d (8)

36. If a load of 9 kg is suspended on a wire, the increase in length is 4.5 mm. The force constant of the wire is

(a) 0.49×104 N/m (b) 1.96×104 N/m (c) 4.9×104 N/m (d) 0.196×104 N/m Answer-b (16)

The escape velocity of an object on a planet whose g value is 9 times on earth and whose radius is 4 times that of earth in km/s is

(a) 67.2 (b) 33.6 (c) 16.8 …

44. After effects of elasticity are maximum for

(a) Glass (b) Quartz (c) Rubber (d) Metal Answer-a (17)

43. The elasticity of invar

(a) Increases with temperature rise (b) Decreases with temperature rise (c) Does not depend on temperature (d) None of the above Answer-c (46)

42. The force constant of a wire does not depend on

(a) Nature of the material (b) Radius of the wire (c) Length of the wire (d) None of the above Answer-d (7)

37. The escape velocity of a planet having mass 6 times and radius 2 times as that of earth is

(a) √3 ve (b) 3 ve (c) √2 ve (d) 2 ve Answer: a (6)

39. A steel wire is stretched with a definite load. If the Young’s modulus of the wire is Y. For decreasing the value of Y

(a) Radius is to be decreased (b) Radius is to be increased (c) Length is to be increased (d) None of the above ANSWER-D (11)

‘Celanese silk’ is

a. Cellulose trinitrate b. Cellulose acetate c. Cellophane d. Pyroxylin Ans. b (6)

Which of the following is currently used as a tyre cord

a. Terylene b. Polyethylene c. Polypropylene d. Nylon- 6 Ans. d (11)

35. A weight of 200 kg is suspended by vertical wire of length 600.5 cm. The area of cross-section of wire is 1mm2. When the load is removed, the wire contracts by 0.5 cm. The Young’s modulus of the material of wire will be

(a) 2.35×1012 N/m2 (b) 1.35×1010 N/m2 (c) 13.5×1011 N/m2 (d) 23.5×109 N/m2 Answer- (8)

The polymer used for making contact lenses for eyes is

a. Polymethylmethacrylate b. Polyethylene c. Polyethylacrylate d. Nylon – 6 Ans. a (5)

144. A ring of radius 4a is rigidly fixed in vertical position on a table. A small disc of mass m and radius a is released as shown in the fig. When the disc rolls down, without slipping, to the lowest point of the ring, then its speed will be

(a) √ga (b) √2ga (c) √3ga (d) √4ga Ans. d (133)

Plexiglass is a commercial name of

a. Glyptal b. Polyacrylo nitrile c. Polythylacrylate d. Polyethyl acrylate Ans. a (43)

34. Two wires of copper having the length in the ratio 4 : 1 and their radii ratio as 1 : 4 are stretched by the same force. The ratio of longitudinal strain in the two will be

(a) 1 : 16 (b) 16 : 1 (c) 1 : 64 (d) 64 : 1 Answer-b (2)

Which of the following has been used in the manufacture of non- inflammable photographic films

a. Cellulose nitrate b. Cellulose acetate c. Cellulose xanthate d. Cellulose perchlorate Ans. b (5)

The escape velocity from the surface of earth is Ve . The escape velocity from the surface of a planet whose mass and radius are 3 times those of the earth will be

(a) Ve (b) 3 Ve (c) 9 Ve (d) 27 Ve Answer: a (4)

Which of the following statements about low density polythene is FALSE

a. It is poor conductor of electricity b. Its synthesis required dioxygen or a peroxide initiator as a catalyst c. It is used in the manufacture of buckets, dust-bins etc d. Its synthesis requires high pressure Ans. b (6)

Polymer used in bullet proof glass is

a. Lexan b. PMMA c. Nomex d. Kevlar Ans. a (7)

The mass of the earth is 81 times that of the moon and the radius of the earth is 3.5 times that of the moon. The ratio of the escape velocity on the surface of earth to that on the surface of moon will be

(a) 0.2 (b) 2.57 (c) 4.81 (d) 0.39 Answer: c (2)

142. A solid ball of mass m and radius r rolls without slipping along the track shown in the fig. The radius of the circular part of the track is R. The ball starts rolling down the track from rest from a height of 8R from the ground level. When the ball reaches the point P then its velocity will be

(a) √(gR) (b) √(5gR) (c) √(10gR) (d) √(3gR) Ans. c (21)

Wash and wear clothes are manufactured using

a. Nylon fibres b. Cotton mixed with nylon c. Terylene fibres d. Wool fibres Ans. c (40)

Escape velocity on a planet is ve . If radius of the planet remains same and mass becomes 4 times, the escape velocity becomes

(a) 4 ve (b) 2 ve (c) ve …

Terylene is used for making

a. Silks b. Fabrics c. Seat belts d. All of these Ans. d (7)

Which polymer is used for making magnetic recording tapes

a. Dacron b. Acrilan c. Glytal d. Bakelite Ans. d (8)

Which one of the following is used to make ‘non-stick’ cookware

a. PVC b. polystyrene c. Polyethylene terephthalate d. Polyetrafloureothylene Ans. d (19)

The escape velocity of an object from the earth depends upon the mass of the earth (M), its mean density (p), its radius (R) and the gravitational constant (G). Thus the formula for escape velocity is

Answer: a (5)

If g is the acceleration due to gravity at the earth’s surface and r is the radius of the earth, the escape velocity for the body to escape out of earth’s gravitational field is

(a) gr (b) √2gr (c) g/r (d) r/g Answer: b (4)

Which of the following compounds is a constituent of he polymer

a. Methylamine b. N- Methyl urea c. Formaldehyde d. Ammonia Ans.c (7)

Year: 2022

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