Tiêu đề 11.THERMAL PROPERTIES OF MATTER - Questions.pdf ✅

11.THERMAL PROPERTIES OF MATTER – Questions (1.)An amount of water of mass 20 g at 0°C is mixed with 40 g of water 10°C, final temperature of the mixture is (a.) 5°C (b.) 0°C (c.) 20°C (d.) 6.66°C (2.)The surface temperature of the stars is determined using (a.) Planck’s law (b.) Wien’s displacement law (c.) Rayleigh-Jeans law (d.) Kirchhoff’s law (3.)Assuming the sun to be a spherical body of radius R at a temperature of T K, evaluate the total radiant power, incident on earth, at a distance r from the sun Where r0is the radius of the earth and σ is stefan’s constant.v (a.) 4πr0 2R 2σT 4 r 2 ⁄ (b.) πr0 2R 2σT 4 r 2 ⁄ (c.) r0 2R 2σT 4 4πr 2 ⁄ (d.) R 2σT 4 r 2 ⁄ (4.)Which one of the following would raise the temperature of 20 g of water at 30°C most when mixed with it? (a.) 20 g of water at 40°C (b.) 40 g of water at 35 °C (c.) 10 g of water at 50°C (d.) 4 g water at 80°C (5.)A cylinder of radius R made of a material of thermal conductivity K1 is surrounded by a cylindrical shell of inner radius R and outer radius 2R made of material of thermal conductivity K2. The two ends of the combined system are maintained at two different temperatures. There is no loss of heat across the cylindrical surface and the system is in steady state. The effective thermal conductivity of the system is (a.) K1 + K2 (b.) K1K2 K1+K2 (c.) K1+3K2 4 (d.) 3K1+K2 4 (6.)Which one of the figure gives the temperature dependence of density water correctly? (a.) (b.) (c.) (d.) (7.)If mass-energy equivalence is taken into account, when water is cooled to form ice, the mass of water should (a.) Increase (b.) Remain unchanged (c.) Decrease (d.) First increase then decrease (8.)‘Stem Correction’ in platinum resistance thermometers are eliminated by the use of (a.) Cells (b.) Electrodes (c.) Compensating leads (d.) None of the above (9.)A body, which emits radiations of all possible wavelengths, is known as (a.) Good conductor (b.) Partial radiator (c.) Absorber of photons (d.) Perfectly black-body (10.)The amount of work, which can be obtained by supplying 200 cal of heat, is
(a.) 840 dyne (b.) 840 W (c.) 840 erg (d.) 840 J (11.)The ends of two rods of different materials with their thermal conductivities, radii of cross-sections and lengths all are in the ratio 1:2 are maintained at the same temperature difference. If the rate of flow of heat in the larger rod is 4 cal/s, that in the shorter rod in cal/s will be (a.) 1 (b.) 2 (c.) 8 (d.) 16 (12.)Density of substance at 0°C is 10 g/cc and at 100°C, its density is 9.7 g/cc. The coefficient of linear expansion of the substance is (a.) 1.03 × 10−4 (b.) 3 × 10−4 (c.) 19.7 × 10−3 (d.) 10−3 (13.)A lead bullet at 27°C just melts when stopped by an obstacle. Assuming that 25% of heat is absorbed by the obstacle, then the velocity of the bullet at the time of striking (M.P. of lead = 327°C, specific heat of lead = 0. 03cal/g°C, latent heat of fusion of lead = 6cal/g and J = 4. 2joule/cal) (a.) 410m/s (b.) 1230m/s (c.) 307. 5m/s (d.) None of the above (14.)The absolute zero is the temperature at which (a.) Water freezes (b.) All substances exist in solid state (c.) Molecular motion ceases (d.) None of the above (15.)If a cylinder a diameter 1. 0 cm at 30°C is to be fitted into a hole of diameter 0. 9997 cm in a steel plate at the same temperature, then minimum required rise in the temperature of the plate is : (Coefficient of linear expansion of steel = 12 × 10−6 /°C) (a.) 25°C (b.) 35°C (c.) 45°C (d.) 55°C (16.)Two identical bodies have temperatures 277°C and 67°C . If the surroundings temperature is 27°C, the ratio of loss of heats of the two bodies during the same interval of time is(approximately) (a.) 4:1 (b.) 8:1 (c.) 12:1 (d.) 19:1 (17.)A lead bullet strikes against a steel plate with a velocity 200 m/s. If the impact is perfectly inelastic and the heat produced is equally shared between the bullet and the target, then the rise in temperature of the bullet is (specific heat capacity of lead=125Jkg−1 K −1 ) (a.) 80°C (b.) 60°C (c.) 40°C (d.) 120°C (18.)Two walls of thicknesses d1 and d2 and thermal conductivities k1 and k2 are in contact. In the steady state, if the temperatures at the outer surfaces are T1 and T2, the temperature at the common wall is (a.) k1T1d2+k2T2d1 k1d2+k2d1 (b.) k1T1+k2d2 d1+d2 (c.) ( k1d1+k2d2 T1+T2 ) T1T2 (d.) k1d1T1+k2d2T2 k1d1+k2d2 (19.)Ratio among linear expansion coefficient (α), areal expansion coefficient (β) and volume expansion coefficient (γ) is (a.) 1 ∶ 2 ∶ 3 (b.) 3 ∶ 2 ∶ 1 (c.) 4 ∶ 3 ∶ 2 (d.) None of these (20.)On a hilly region, water boils at 95°C.The temperature expressed in Fahrenheit is (a.) 100°F (b.) 20. 3°F (c.) 150°F (d.) 203°F (21.)The temperature at which a black body of unit area loses its energy at the rate of 1 joule/second is (a.) −65°C (b.) 65°C (c.) 65 K (d.) None of these (22.)The thermal capacity of 40 g of aluminium (specific heat = 0.2 cal/g/°C) is (a.) 40 cal/°C (b.) 160 cal/°C (c.) 200 cal/°C (d.) 8 cal/°C (23.)One quality of a thermometer is that its heat capacity should be small. If P is a mercury
thermometer, Q is a resistance thermometer and R thermocouple type then (a.) P is best, R worst (b.) R is best, P worst (c.) R is best, Q worst (d.) P is best, Q worst (24.)An ideal gas is expanding such that PT 2 = constant. The coefficient of volume expansion of the gas is (a.) 1 T (b.) 2 T (c.) 3 T (d.) 4 T (25.)The two ends of a rod of length L and a uniform cross-sectional area A are kept at two temperature T1 and T2 (T1 > T2). The rate of heat transfer, dQ dt , through the rod in a steady state is given by (a.) dQ dt = kL(T1−T2) A (b.) dQ dt = k(T1−T2) LA (c.) dQ dt = kLA(T1 − T2) (d.) dQ dt = kA(T1−T2) L (26.)The maximum energy in thermal radiation from a source occurs at the wavelength 4000Å. The effective temperature of the source is (a.) 7325 K (b.) 800 K (c.) 104 K (d.) 106 K (27.)A body cools in a surrounding which is at a constant temperature of θ0. Assume that of obeys Newton’s law of cooling. Its temperature θ is plotted against time t. Tangents are drawn to the curve at the points P(θ = θ2) and Q(θ = θ1). These tangents meet the time axis at angles of φ2 and φ1, as shown (a.) tan φ2 tan φ1 = θ1−θ0 θ2−θ0 (b.) tan φ2 tan φ1 = θ2−θ0 θ1−θ0 (c.) tan φ1 tan φ2 = θ1 θ2 (d.) tan φ1 tan φ2 = θ2 θ1 (28.)A closed bottle containing water at 30°C is carried to the moon in a space-ship. If it is placed on the surface of the moon, what will happen to the water as soon as the lid is opened (a.) Water will boil (b.) Water will freeze (c.) Nothing will happen on it (d.) It will decompose into H2 and O2 (29.)Three objects coloured black, gray and white can with stand hostile conditions at 2800°C. These objects are thrown into furnace where each of them attains a temperature of 2000°C. Which object will glow brightest? (a.) The white object (b.) The black object (c.) All glow with equal brightness (d.) Gray object (30.)The temperature of the two outer surfaces of a composite slab, consisting of two materials having coefficients of thermal conductivity K and 2K and thickness x and 4x, respectively are T2 and T1 (T2 > T1). The rate of heat transfer through the slab, in a steady state is ( A(T2−T1)K x ) f, with f equals to (a.) 1 (b.) 1/3 (c.) 2/3 (d.) 1/3 (31.)If temperature of a black body increases from 7°C to 287°C, then the rate of energy radiation increases by (a.) ( 287 7 ) 4 (b.) 16 (c.) 4 (d.) 2 (32.)The figure shows a glass tube (linear co-efficient of expansion is α) completely filled with a liquid of volume expansion co-efficient γ. On heating length of the liquid column does not change. Choose the correct relation between γ and α t P Q  2 1 0 2 1 2 T 2 K 2 K x
(a.) γ = α (b.) γ = 2α (c.) γ = 3α (d.) γ = α 3 (33.)The heat is flowing through two cylindrical rods of same material. The diameters of the rods are in the ratio 1:2 and their lengths are in the ratio 2:1. If the temperature difference between their ends is the same, the ratio of rate of flow of heat through them will be (a.) 1 : 1 (b.) 2 : 1 (c.) 1 : 4 (d.) 1 : 8 (34.)The temperature of two bodies A and B are 727°C and 127°C. The ratio of rate of emission of radiations will be (a.) 727/127 (b.) 625/16 (c.) 1000/400 (d.) 100/16 (35.)For an opaque body coefficient of transmission is (a.) Zero (b.) 1 (c.) 0.5 (d.) ∞ (36.)If a liquid is heated in weightlessness, the heat is transmitted through (a.) Conduction (b.) Convection (c.) Radiation (d.) Neither, because the liquid cannot be heated in weightlessness (37.)Two spheres of radii 8 cm and 2 cm are cooling. Their temperatures are 127°C and 527°C respectively. Find the ratio of energy radiated by them in the same time (a.) 0.06 (b.) 0.5 (c.) 1 (d.) 2 (38.)When a rod is heated but prevented from expanding, the stress developed is independent of (a.) Material of the rod (b.) Rise in temperature (c.) Length of rod (d.) None of above (39.)Thermoelectric thermometer is based on (a.) Photoelectric effect (b.) Seebeck effect (c.) Compton effect (d.) Joule effect (40.)A hot metallic sphere of radius r radiates heat. It’s rate of cooling is (a.) Independent of r (b.) Proportional to r (c.) Proportional to r 2 (d.) Proportional to 1/r (41.)A rod of length 20 cm is made of metal. It expands by 0. 075cm when its temperature is raised from 0°C to 100°C. Another rod of a different metal B having the same length expands by 0.045 cm for the same change in temperature. A third rod of the same length is composed of two parts, one of metal A and the other of metal B. This rod expands by 0.060 cm for the same change in temperature. The portion made of metal A has the length (a.) 20 cm (b.) 10 cm (c.) 15 cm (d.) 18 cm (42.)A body takes 5 minutes for cooling from 50°C to 40°C. Its temperature comes down to 33.33°C in next 5 minutes. Temperature of surroundings is (a.) 15°C (b.) 20°C (c.) 25°C (d.) 10°C (43.)Assuming the sun to have a spherical outer surface of radius r, radiating like a black body at temperature t°C, the power received by a unit surface, (normal to the incident rays) at a distance R from the centre of the sun is Where σ is the stefan’s constant. (a.) 4πr 2σt 4 R2 (b.) r 2σ(t+273) 4 4πR2 (c.) 16π 2r 2σt 4 R2 (d.) r 2σ(t+273) 4 R2 (44.)A wire 3 m in length and 1 mm in diameter at 30°C is kept in a low temperature at −170°C and is stretched by hanging a weight of 10 kg at one end. The change in length of the wise is (Y = 2 × 1011 Nm−2 , g=10ms−2 and α = 1. 2 × 10−5 °C−1 ) (a.) 5.2 mm l0 A0