Practice Test

Q1) The temperature and pressure at which all the three phases of a substance coexist is called the Show Answer

Q2) The SI unit of thermal conductivity (K) is Show Answer

Q3) The triple point of carbon dioxide is 216.55 K . This temperature on the Fahrenheit scale is Show Answer

Q4) Estimate the ratio of their number of molecules. Show Answer

Q5) Estimate the mass densities of Neon to Oxygen in vessel. Show Answer

Q6) Obtain the ratio of average kinetic energy per molecule of argon to chlorine. Show Answer

Q7) By what percentage should the pressure of a given mass of a gas be increased so as to decrease its volume by 10% at a constant temperature? Show Answer

Q8) The equation PV = n R T can safely describe the behavior of a real gas at Show Answer

Q9) Boyle's law is applicable in Show Answer

Q10) The order of magnitude of the number of nitrogen molecules in an air bubble of diameter 2 mm under ordinary conditions is Show Answer

Q11) At a constant pressure, of the following graphs the one which represents the variation of the density of an ideal gas with the absolute temperature T, is Show Answer

Q12) Statement 1 : Real gas approaches ideal gas behaviour for low pressure and low temperatures.
Statement 2 : At low pressure, density of gas is very low. Show Answer

Q13) Statement 1 : All molecules in a gas move with same speed.
Statement 2 : Average velocity of a gas sample is zero. Show Answer

Q14) What is the total kinetic energy of all the molecules of two gases before mixing? Show Answer

Q15) If T is the temperature of the mixture, then the total kinetic energy of the two gases after mixing is : Show Answer

Q16) The temperature T of the mixture is : Show Answer

Q17) The perfect gas equation for 4 gram of hydrogen gas is Show Answer

Q18) If the volume of the gas is to be increased by 4 times, Show Answer

Q19) In the kinetic theory of gases, which of these statements is/are true?
(i) The pressure of a gas is proportional to the mean speed of the molecules.
(ii) The root mean square speed of the molecules is proportional to the pressure.
(iii) The rate of diffusion is proportional to the mean speed of the molecules.
(iv) The mean translational kinetic energy of a gas is proportional to its Kelvin temperature. Show Answer

Q20) The rms speed of a gas molecule is Show Answer

Q21) According to kinetic theory of gases, at absolute zero of temperature, Show Answer

Q22) Which of the following statements is not in accordance with the assumptions made in kinetic theory? Show Answer

Q23) The X-components of velocities of some particles (in km//s) came to be 10, 8, 6, 4, 2, 0, -2, -4, -6, -8, -10. The root mean square (rms) velocity calculated from these data (in km/s) is nearest to Show Answer

Q24) Statement 1 : If we compress a gas sample kept in a container, pressure increases.
Statement 2 : Frequency of collisions of atoms increases. Show Answer

Q25) Statement 1 : Internal energy of a gas sample is total kinetic energy of gas.
Statement 2 : There is no interaction force between gas molecules hence potential energy is not defined. Show Answer

Q26) Momentum transferred to wall in one collision is Show Answer

Q27) Which of the following is not true for a gas sample? Show Answer

Q28) Every gas (real gas) behaves as an ideal gas Show Answer

Q29) Boyle's law holds for an ideal gas during Show Answer

Q30) S.I. unit of universal gas constant is Show Answer

Q31) Molecules of a gas behave like Show Answer

Q32) At absolute zero temperature, pressure of a gas will be Show Answer

Q33) The gas which obeys Boyle's law for maximum range of temperature is Show Answer

Q34) The temperature below which a gas should be cooled, before it can be liquified by pressure only is termed as Show Answer

Q35) It is possible for a substance to coexist in all three phases in equilibrium, when the substance is at Show Answer

Q36) When air is filled in the balloon, the pressure and volume both increases while temperature does not change. Here Boyle's law is not obeyed because Show Answer

Q37) For Boyle's law to hold the gas should be Show Answer

Q38) Which of the following statements about kinetic theory of gases is wrong Show Answer

Q39) If a Vander-Waal's gas expands freely, then final temperature is Show Answer

Q40) At NTP, sample of equal volume of chlorine and oxygen is taken. Now ratio of No. of molecules Show Answer

Q41) A gas at the temperature 250 K is contained in a closed vessel. If the gas is heated through 1K, then the percentage increase in its pressure will be Show Answer

Q42) A cylinder of 5 litre capacity, filled with air at N.T.P. is connected with another evacuated cylinder of 30 litres of capacity. The resultant air pressure in both the cylinders will be Show Answer

Q43) Volume of gas become four times if Show Answer

Q44) Kinetic theory of gases provide a base for Show Answer

Q45) At constant temperature on increasing the pressure of a gas by 5% will decrease its volume by Show Answer

Q46) Which law states that effect of pressure is same for all portion Show Answer

Q47) When the pressure on 1200 ml of a gas in increased from 70 cm to 120 cm of mercury at constant temperature, the new volume of the gas will be Show Answer

Q48) Under which of the following conditions is the law PV = RT obeyed most closely by a real gas Show Answer

Q49) That gas cannot be liquified Show Answer

Q50) At NTP the mass of one litre of air is 1.293 gm. The value of specific gas constant will be Show Answer

Q51) For one gram mol of a gas, the value of R in the equation PV = RT is nearly Show Answer

Q52) We write the relation for Boyle's law in the form PV = C when the temperature remains constant. In this relation, the magnitude of C depends upon Show Answer

Q53) A sample of an ideal gas occupies a volume V at a pressure P and absolute temperature T, the mass of each molecule is m. The expression for the density of gas is (k = Boltzmann’s constant) Show Answer

Q54) The product of the pressure and volume of an ideal gas is Show Answer

Q55) For ideal gas, which statement is not true Show Answer

Q56) Kinetic theory of gases was put forward by Show Answer

Q57) When volume of system is increased two times and temperature is decreased half of its initial temperature, then pressure becomes Show Answer

Q58) The equation of state for 5 g of oxygen at a pressure P and temperature T, when occupying a volume V, will be Show Answer

Q59) The pressure and temperature of two different gases is P and T having the volume V for each. They are mixed keeping the same volume and temperature, the pressure of the mixture will be Show Answer

Q60) At a given volume and temperature, the pressure of a gas Show Answer

Q61) The rate of diffusion is Show Answer

Q62) For matter to exist simultaneously in gas and liquid phases Show Answer

Q63) The value of critical temperature in terms of Vander Waal’s constant a and b is Show Answer

Q64) Air is filled in a bottle at atmospheric pressure and it is corked at 35°C. If the cork can come out at 3 atmospheric pressure than upto what temperature should the bottle be heated in order to remove the cork Show Answer

Q65) 125 ml of gas A at 0.60 atmosphere and 150 ml of gas B at 0.80 atmosphere pressure at same temperature is filled in a vessel of 1 litre volume. What will be the total pressure of mixture at the same temperature Show Answer

Q66) Saturated vapour is compressed to half its volume without any change in temperature, then the pressure will be Show Answer

Q67) What is the mass of 2 litres of nitrogen at 22.4 atmospheric pressure and 273K Show Answer

Q68) The value of PV/T for one mole of an ideal gas is nearly equal to Show Answer

Q69) A tyre kept outside in sunlight bursts off after sometime because of Show Answer

Q70) In Boyle's law what remains constant Show Answer

Q71) In Boyle's law what remains constant Show Answer

Q72) The r.m.s. velocity will be greater for Show Answer

Q73) In thermal equilibrium, the average velocity of gas molecules is Show Answer

Q74) The absolute temperature of a gas is determined by Show Answer

Q75) For a gas, the r.m.s. speed at 800 K is Show Answer

Q76) The root mean square velocity of a gas molecule of mass m at a given temperature is proportional to Show Answer

Q77) A gas is allowed to expand isothermally. The root mean square velocity of the molecules Show Answer

Q78) Moon has no atmosphere because Show Answer

Q79) Speed of sound in a gas is v and r.m.s. velocity of the gas molecules is c. The ratio of v to c is Show Answer

Q80) Which of the following statement is true Show Answer

Q81) Two vessels having equal volume contains molecular hydrogen at one atmosphere and helium at two atmospheres respectively. If both samples are at the same temperature, the mean velocity of hydrogen molecules is Show Answer

Q82) According to the kinetic theory of gases the r.m.s. velocity of gas molecules is directly proportional to Show Answer

Q83) At a given temperature the root mean square velocities of oxygen and hydrogen molecules are in the ratio Show Answer

Q84) r.m.s. velocity of nitrogen molecules at NTP is Show Answer

Q85) The temperature of an ideal gas is increased from 120 K to 480 K. If at 120 K, the root mean square velocity of the gas molecules is v, at 480 K it becomes Show Answer

Q86) The root mean square speed of the molecules of a gas is Show Answer

Q87) At a given temperature the r.m.s. velocity of molecules of the gas is Show Answer

Q88) The speeds of 5 molecules of a gas (in arbitrary units) are as follows : 2, 3, 4, 5, 6. The root mean square speed for these molecules is Show Answer

Q89) At a given temperature the ratio of r.m.s. velocities of hydrogen molecule and helium atom will be Show Answer

Q90) Cooking gas containers are kept in a lorry moving with uniform speed. The temperature of the gas molecules inside will Show Answer

Q91) The r.m.s. speed of a group of 7 gas molecules having speeds (6, 4, 2, 0, – 2, – 4, – 6) m/s is Show Answer

Q92) Molecular motion shows itself as Show Answer

Q93) According to the kinetic theory of gases, at absolute temperature Show Answer

Q94) The r.m.s. speed of gas molecules is given by Show Answer

Q95) If the pressure in a closed vessel is reduced by drawing out some gas, the mean free path of the molecules Show Answer

Q96) At constant volume, temperature is increased. Then Show Answer

Q97) A monoatomic gas molecule has Show Answer

Q98) For an ideal gas of diatomic molecules Show Answer

Q99) At constant volume, for different diatomic gases the molar specific heat is Show Answer

Q100) The relation between two specific heats of a gas is Show Answer

Q101) The specific heat of an ideal gas is Show Answer

Q102) Supposing the distance between the atoms of a diatomic gas to be constant, its specific heat at constant volume per mole (gram mole) is Show Answer

Q103) The specific heats at constant pressure is greater than that of the same gas at constant volume because

Show Answer

Q104) The specific heat of a gas Show Answer

Q105) The molar specific heat at constant pressure for a monoatomic gas is Show Answer

Q106) Which of the following formulae is wrong Show Answer

Q107) The quantity of heat required to raise one mole through one degree Kelvin for a monoatomic gas at constant volume is Show Answer

Q108) The specific heat relation for ideal gas is Show Answer

Q109) If two moles of diatomic gas and one mole of mono atomic gas are mixed then the ratio of specific heats is

Show Answer

Q110) The kinetic energy, due to translational motion, of most of the molecules of an ideal gas at absolute temperature T is Show Answer

Q111) The ratio of specific heat of a mixture of one mole of helium and one mole of hydrogen gas will be Show Answer

Q112) If a gas has n degrees of freedom ratio of specific heats of gas is Show Answer

Q113) The degrees of freedom of a stationary rigid body about its axis will be Show Answer

Q114) The pressure exerted by the gas on the walls of the container because Show Answer

Q115) In kinetic theory of gases, a molecule of mass m of an ideal gas collides with a wall of vessel with velocity V. The change in the linear momentum of the molecule is Show Answer

Q116) If the mean free path of atoms is doubled then the pressure of gas will become Show Answer

Q117) Relationship between and for a gas is Show Answer

Q118) The ratio of mean kinetic energy of hydrogen and oxygen at a given temperature is Show Answer

Q119) According to the kinetic theory of gases, total energy of a gas is equal to Show Answer

Q120) The average kinetic energy of a gas molecule can be determined by knowing Show Answer

Q121) Mean kinetic energy (or average energy) per gm molecule of a monoatomic gas is given by Show Answer

Q122) A sealed container with negligible coefficient of volumetric expansion contains helium (a monoatomic gas). When it is heated from 300 K to 600 K, the average K.E. of helium atoms is Show Answer

Q123) The time average of the kinetic energy of one molecule of a gas taken over a long period of time Show Answer

Q124) The kinetic energy per gm mol for a diatomic gas at room temperature is Show Answer

Q125) The translatory kinetic energy of a gas per gm is Show Answer

Q126) Read the given statements and decide which is/are correct on the basis of kinetic theory of gases [MP PMT 2003]
(I) Energy of one molecule at absolute temperature is zero
(II) r.m.s. speeds of different gases are same at same temperature
(III) For one gram of all ideal gas kinetic energy is same at same temperature
(IV) For one mole of all ideal gases mean kinetic energy is same at same temperature
Show Answer

Q127) The translational kinetic energy of gas molecule for one mole of the gas is equal to Show Answer

Q128) At 0 K which of the following properties of a gas will be zero Show Answer

Q129) At the same temperature and pressure and volume of two gases, which of the following quantities is constant Show Answer

Q130) On absolute temperature, the kinetic energy of the molecules Show Answer

Q131) On colliding in a closed container the gas molecules Show Answer

Q132) Vapour is injected at a uniform rate in a closed vessel which was initially evacuated. The pressure in the vessel Show Answer

Q133) The molecules of an ideal gas at a certain temperature have Show Answer

Q134) Mean kinetic energy per degree of freedom of gas molecules is Show Answer

Q135) In kinetic theory of gases, which of the following statements regarding elastic collisions of the molecules is wrong Show Answer

Q136) An ideal gas is filled in a vessel, then Show Answer

Q137) A gas is filled in a cylinder, its temperature is increased by 20% on Kelvin scale and volume is reduced by 10%. How much percentage of the gas will leak out Show Answer

Q138) From the following statements, concerning ideal gas at any given temperature T, select the correct one(s) Show Answer

Q139) A closed compartment containing gas is moving with some acceleration in horizontal direction. Neglect effect of gravity. Then the pressure in the compartment is Show Answer

Q140) A gas in container A is in thermal equilibrium with another gas in container B. both contain equal masses of the two gases in the respective containers. Which of the following can be true Show Answer

Q141) A closed vessel contains 8gm of oxygen and 7gm of nitrogen. The total pressure is 10 atm at a given temperature. If now oxygen is absorbed by introducing a suitable absorbent the pressure of the remaining gas in atm will be Show Answer

Q142) If the intermolecular forces vanish away, the volume occupied by the molecules contained in 4.5 kg water at standard temperature and pressure will be Show Answer

Q143) The temperature at which the r.m.s. speed of hydrogen molecules is equal to escape velocity on earth surface, will be Show Answer

Q144) Inside a cylinder having insulating walls and closed at ends is a movable piston, which divides the cylinder into two compartments. On one side of the piston is a mass m of a gas and on the other side a mass 2 m of the same gas. What fraction of volume of the cylinder will be occupied by the larger mass of the gas when the piston is in equilibrium ? Consider that the movable piston is conducting so that the temperature is the same throughout Show Answer

Q145) A gas mixture consists of 2 mole of oxygen and 4 mole of argon at temperature T. Neglecting all vibrational modes, the total internal energy of the system is Show Answer

Q146) A jar contains a gas and few drops of water at T K. The pressure in the jar is 830 mm of mercury. The temperature of jar is reduced by 1%. The saturated vapour pressure of water at the two temperatures are 30 mm and 25 mm of mercury. Then the new pressure in the jar will be Show Answer

Q147) Which one the following graphs represents the behaviour of an ideal gas Show Answer

Q148) Assertion : In pressure-temperature (P-T) phase diagram of water, the slope of the melting curve is found to be negative.
Reason : Ice contracts on melting to water.
Show Answer

Q149) Assertion : A gas have a unique value of specific heat.
Reason : Specific heat is defined as the amount of heat required to raise the temperature of unit mass of the substance through unit degree.
Show Answer

Q150) Assertion :A gas can be liquified at any temperature by increase of pressure alone.
Reason : On increasing pressure the temperature of gas decreases.
Show Answer

Q151) Assertion :Equal masses of helium and oxygen gases are given equal quantities of heat. There will be a greater rise in the temperature of helium compared to that of oxygen.
Reason :The molecular weight of oxygen is more than the molecular weight of helium.
Show Answer

Q152) Assertion :Absolute zero is the temperature corresponding to zero energy.
Reason :The temperature at which no molecular motion cease is called absolute zero temperature.
Show Answer

Q153) Assertion :The ratio of specific heat gas at constant pressure and specific heat at constant volume for a diatomic gas is more than that for a monatomic gas.
Reason :The molecules of a monatomic gas have more degree of freedom than those of a diatomic gas. Show Answer

Q154) Assertion :At room temperature, water does not sublimate from water to steam.
Reason : The critical point of water is much above the room temperature.
Show Answer

Q155) Assertion :Specific heat of a gas at constant pressure (CP) is greater than its specific heat at constant volume (CV).
Reason : At constant pressure, some heat is spent in expansion of the gas.
Show Answer

Q156) Assertion :The internal energy of a real gas is function of both, temperature and volume.
Reason : Internal kinetic energy depends on temperature and internal potential energy depends on volume.
Show Answer

Q157) Assertion :For an ideal gas, at constant temperature, the product of the pressure and volume is constant.
Reason : The mean square velocity of the molecules is inversely proportional to mass.
Show Answer

Q158) Assertion :If a gas container in motion is suddenly stopped, the temperature of the gas rises.
Reason : The kinetic energy of ordered mechanical motion is converted in to the kinetic energy of random motion of gas molecules.
Show Answer

Q159) Assertion :Internal energy of an ideal gas does not depend upon volume of the gas
Reason : Internal energy of ideal gas depends on temperature of gas.
Show Answer

Q160) Assertion :Maxwell speed distribution graph is symmetric about most probable speed
Reason : rms speed of ideal gas, depends upon it's type (monoatomic, diatomic and polyatomic)
Show Answer

Q161) A vessel contains 60,000 molecules of a gas. Due to a very fine hole in the wall, 10,000 molecules escape from the vessel. Then the mean free path of the molecules of the gas Show Answer

Q162) There are N molecules of a gas in a box. If the number of molecules is increased to 2N, then the r.m.s. speed of the molecules will Show Answer

Q163) If the temperature of an enclosed gas is slowly increased at constant volume, then Show Answer

Q164) The root mean square velocity of the molecules of a gas is 200 m/s. What will be the rms velocity of the molecules if the atomic weight is doubled and the absolute temperature is halved? Show Answer

Q165) Molecular weight of oxygen is 32 and that of hydrogen is 2. The ratio of the rms velocity of hydrogen molecule at 400 K to rms velocity of oxygen molecule at 900 K is given by Show Answer

Q166) If the absolute temperature of a gas is increased 3 times, the root mean square velocity of the molecules of the gas will be Show Answer

Q167) The velocities of 5 molecules are 2 m/s, 3 m/s, 4 m/s, 5 m/s and 6 m/s respectively. What is their mean velocity? Show Answer

Q168) The velocities of 4 molecules are 2 m/s, 4 m/s, 5 m/s and 6 m/s respectively. What is their mean square velocity? Show Answer

Q169) The translational K.E. of the molecules of a gas at absolute temperature (T) can be doubled Show Answer

Q170) A vessel contains one mole of oxygen and one mole of hydrogen at N.T.P. What is the ratio of the values of rms velocities of hydrogen and oxygen molecules? Show Answer

Q171) Which one of the following gas molecules has the maximum r.m.s. speed at a given temperature? Show Answer

Q172) The phenomenon of Brownian motion is taken as an evidence of Show Answer

Q173) The molecules of an ideal gas, possess Show Answer

Q174) The number of molecules in a gram molecule of a gas is called Show Answer

Q175) When a gas is compressed by keeping the temperature constant, the collision frequency of the gas molecules Show Answer

Q176) At a certain temperature, hydrogen molecules have r.m.s. velocity of 3 km/s. What is the r.m.s. velocity of the oxygen molecules at the same temperature? Show Answer

Q177) At what temperature, the r.m.s. speed of the molecules of a gas is half its value at NTP? Show Answer

Q178) The r.m.s. velocity of the molecules of an ideal gas is C at a temperature of 100 K. At what temperature its r.m.s. velocity will be doubted? Show Answer

Q179) The velocities of 4 molecules are 2 m/s, 4 m/s, 5 m/s and 6 m/s. What is the difference between their rms speed and average speed? Show Answer

Q180) If the absolute temperature of a gas is increased 5 times, the r.m.s. velocity of the molecules will be Show Answer

Q181) The r.m.s. velocity of the gas molecules is 300 m/s. What will be the r.m.s. velocity of the molecules if the atomic weight is doubled and the absolute temperature is halved? Show Answer

Q182) The r.m.s. velocity of the molecules of a gas is 200 m/s. What is the r.m.s. velocity of the molecules of a gas with twice the molecular weight and half the absolute temperature? Show Answer

Q183) Find the wrong statement from the following:
According to kinetic theory of gases 0 K is that temperature at which
Show Answer

Q184) Moon has no atmosphere because Show Answer

Q185) The speeds of four gas molecules are 1 km/s, 3 km/s, 5 km/s and 7 km/s respectively. The difference between their r.m.s. speed and average speed is Show Answer

Q186) If a gas is compressed isothermally, then the rms velocity of its molecules Show Answer

Q187) A perfect gas of volume 10 litre is compressed isothermally to a volume of 1 litre, the rms speed of the molecules will Show Answer

Q188) The mean free path of the molecules of a gas, (radius 'r') is inversely proportional to Show Answer

Q189) The rms velocity of a particle is v at pressure P. If the pressure increases by two times, then its rms velocity will be Show Answer

Q190) The dimensional equation for the universal gas constant is Show Answer

Q191) Air in a cylinder is suddenly compressed by a piston, which is then maintained at the same position. With the passage of time Show Answer

Q192) The temperature of an ideal gas is increased from 100K to 400K. If x is the R.M.S. velocity of its molecules at 100K, then at 400K, it becomes Show Answer

Q193) If we travel from the troposphere to the thermosphere, the mean free path of the air molecules Show Answer

Q194) n balls each of mass m and moving with the same velocity (u) hit a wall elastically and normally in 2 second. The force exerted by the balls on the wall is Show Answer

Q195) A wall is hit elastically and normally by n balls per second. All the balls have the same mass m and are moving with the same velocity u. The force exerted by the balls on the wall is Show Answer

Q196) A molecule of mass m moving with a velocity v makes 5 elastic collisions with a wall of the container per second. The change in its momentum per second will be Show Answer

Q197) The r.m.s. speed of the molecules of an enclosed gas is x. What will be the r.m.s. speed, if the pressure of the gas is doubled but the temperature is kept constant? Show Answer

Q198) If the pressures exerted by two ideal gases are in the ratio 3:2 and their densities are in the ratio 2:1, then the ratio of their r.m.s. velocities is Show Answer

Q199) Gases exert pressure on the walls of the container because the gas molecules Show Answer

Q200) If the masses of all the molecules of a gas are doubled and their speed are halved, then the ratio of the final and initial pressures will be Show Answer

Q201) At the same temperature, the mean kinetic energies of the molecules of hydrogen and oxygen are in the ratio Show Answer

Q202) In case of Boyle's law, if the pressure is increased by 1%, the percentage decrease in volume is Show Answer

Q203) If the pressure of an ideal gas is decreased by 10% isothermally, then its volume will Show Answer

Q204) If E is the kinetic energy per mole of a gas, and T is the absolute temperature, then the universal gas constant is given by Show Answer

Q205) At what temperature will the average K.E. of the hydrogen molecules be half of its value at N.T.P.? Show Answer

Q206) In the Boyle's law experiment, if the volume of the enclosed air is to be decreased from 20 cc to 18 cc; then its pressure should be increased by about Show Answer

Q207) In the expression for Boyle's law, the product 'PV' has the dimensions of Show Answer

Q208) If the kinetic energy per unit volume of an ideal gas is given by E, then the pressure exerted by the gas is Show Answer

Q209) How much should the pressure be increased in order to reduce the volume of a given mass of a gas by 5% at the constant temperature? Show Answer

Q210) At what temperature does the average translational K.E. of a molecule in a gas becomes equal to K.E. of an electron accelerated from rest through potential difference of V volt? All symbols have their usual meaning. Show Answer

Q211) Which one of the following molecules does not possess vibrational energy? Show Answer

Q212) An ideal diatomic gas is heated at constant pressure. What is the fraction of the total energy supplied, which increases the internal energy for the gas? Show Answer

Q213) What is the mean energy per molecule for a polyatomic gas with n degrees of freedom? Show Answer

Q214) A gas mixture consists of 2 moles of oxygen and 4 moles of argon at temperature T. If we neglect all vibrational modes, then the total internal energy of the system will be Show Answer

Q215) One mole of a monoatomic gas is mixed with one mole of a diatomic gas. What is the value of gamma for the mixture if both of them are at the room temperature? Show Answer

Q216) X and Y are two cylinders, fitted with frictionless pistons. Both of them contain equal amounts of oxygen at 200 K. Equal amount of heat is given to the gas in each cylinder. However, the piston of A is fixed while that of B is movable. What is the rise in temperature of the gas in B, if the rise in temperature of A is 42 K? Show Answer

Q217) When a black body is heated, it emits heat radiations of Show Answer

Q218) In which of the following processes, convection of heat does not take place? Show Answer

Q219) Which is not a true statement about black body radiation? Show Answer

Q220) Which one of the following is more close to a black body? Show Answer

Q221) For an opaque body, coefficient of reflection is 0.3. If 200 J of heat energy is incident on it then the heat absorbed by the body will be Show Answer

Q222) If the temperature of the sun is doubled, the rate of energy received on earth will be increased by a factor Show Answer

Q223) If the temperature of a black body becomes half of its original temperature, then the amount of radiation emitted by the body per second will be reduced to Show Answer

Q224) If the temperature of a hot-black body is increased by 10%, the heat energy radiated by it would increase by Show Answer

Q225) The velocity of thermal radiations (V) is related to the velocity of light (C) as Show Answer

Q226) The dimensional formula for Stefan's constant is Show Answer

Q227) Suppose that the sun expands, so that its diameter becomes 10 times its present diameter and its surface temperature becomes half of its present value. Then the total energy emitted by the sun per unit time, will increase by a factor of Show Answer

Q228) Two spheres made of the same material have their radii in the ratio of 2 : 1. What is the ratio of the radiant energy emitted per second by them if both of them are at the same temperature? Show Answer

Q229) The quantity of heat radiated per unit time by a perfectly black body at 300 K is 81 kJ/s. What is the power radiated by a body of emissivity 0.8 and having the same area as that of the black body at 500 K? Show Answer

Q230) A spherical black body of radius 12 cm radiates 450 W power at 500 K. If the radius were halved and the temperature doubled, the power radiated in watt would be Show Answer

Q231) If the temperature of the sun were to increase from T to 2T and its radius from R to 2R, then the ratio of the radiant energy received on the earth to what it was previously will be Show Answer

Q232) The SI unit of Stefan's constant is Show Answer

Q233) A star behaves like a perfectly black body emitting radiant energy. The ratio of the radiant energy radiated per second by this star to that emitted by another star having eight times the radius of the former, but having Kelvin temperature one fourth that of the former is Show Answer

Q234) If the temperature of a black body is increased by 50%, then the percentage increase in its rate of emission will be, approximately equal to Show Answer

Q235) Two spheres A and B of the same materials have radii 1m and 4 m and temperatures 4000 K and 2000 K respectively. If they are coated with materials of the same emissivity, then the heat energy radiated per second by A is Show Answer

Q236) The temperature of the sun is T. If it becomes 2T, then Show Answer

Q237) Assume that the sun is a spherical body of radius R at a temperature of T K. What is the total radiant power, incident on Earth, at a distance r from the sun? Show Answer

Q238) A spherical black body with radius 12 cm radiates 450 W power at 500 K. If the radius were halved and the temperature doubled, what would be the power radiated? Show Answer

Q239) Suppose the sun expands, so that its radius becomes 100 times its present radius and its surface temperature becomes half of its present value. The total energy emitted by the sun will increase by a factor of Show Answer

Q240) The ratio of the wavelengths of emission corresponding to the maximum emission in the spectrum of a black body heated to temperatures 1000K and 2000K respectively is Show Answer

Q241) The light emitted by the sun has the maximum wavelength of 570 nm. The light emitted by another star has the maximum wavelength of 380 nm. What is the ratio of the surface temperatures of the star and the sun? Show Answer

Q242) If the temperature of a black body is doubled, the frequency at which the spectral intensity becomes maximum will be Show Answer

Q243) The phenomenon of black body radiation was explained satisfactorily by Show Answer

Q244) The sun emits light with a maximum wavelength of 510 nm while another star X emits light of maximum wavelength of 350 nm. What is the ratio of the surface temperatures of the sun and the star? Show Answer

Q245) The earth radiates in the infrared region of the spectrum. The wavelength of the maximum intensity of the spectrum is correctly given by Show Answer

Q246) The SI unit of Wien's constant in Wien's displacement law is Show Answer

Q247) The colour of a shining bright star is an indication of its Show Answer

Q248) Two spheres A and B having radii 3 cm and 5 cm respectively are coated with carbon black on their outer surfaces. The wavelengths of maximum intensity of emission of radiation are 300 nm and 500 nm respectively. The respective powers radiated by them are in the ratio of Show Answer

Q249) Which one of the following graphs correctly gives the ideal gas behaviour? Show Answer

Q250) The number of degrees of freedom for a rigid diatomic molecule is Show Answer

Q251) The wavelength range of thermal radiation is Show Answer

Q252) The substance which allows heat radiations to pass through it is Show Answer

Q253) The coefficient of reflection of an opaque body is 0.16. Its coefficient of emission is Show Answer

Q254) Assuming the expression for the pressure exerted by a gas on the walls of the container, it can be shown that the pressure is Show Answer

Q255) An ideal gas has pressure 'P', volume 'V' and absolute temperature 'T'. If 'm' is the mass of each molecule and 'K' is the Boltzmann constant then density of the gas is Show Answer