True/False: Heat & Thermodynamics | JEE Advanced | 35 Years Chapter wise Previous Year Solved Papers for JEE PDF Download

Q.1. The root-mean square speeds of the molecules of different ideal gases, maintained at the same temperature are the same.

Ans. F

Solution. 

i.e., dependent on molar mass and hence rms speed c will be different for different ideal gases.

Q.2. The volume V versus temperature T graphs for a certain amount of a perfect gas at two pressure p₁ and p₂ are as shown in Fig. It follows from the graphs that p₁ is greater than p₂.

Ans. F

Solution. For a particular temperature T 

Volume is greater for pressure P₁

Q.3. Two  different gases at the same temperature have equal root mean square velocities.

Ans. F

Solution. For a particular termperature 

i.e., C_rms will have different values for different gases.

Q.4. The ratio of the  velocity of sound in Hydrogen gas to that  in  Helium gas at the  same temperature is

Ans.F

Solution. 

Q.5. The curves A and B in the figure shown P-V graphs for an isothermal and an adiabatic process for an ideal gas. The isothermal process is represented by the curve A.

Ans. T

Solution. The slope of P-V curve is more for adiabatic process than for isothermal process. From the graph it is clear that slope for B is greater than the slope for A.

Q.6. At a given temperature, the specific heat of a gas at constant pressure is always greater than its specific heat at constant volume.

Ans. T

Solution. C_p – C_v = R

Q.7. The root mean square (rms) speed of oxygen molecules (O₂) at a certain temperature T (degree absolute) is V. If the temperature is doubled and oxygen gas dissociates into atomic oxygen, the rms speed remains unchanged.

Ans.F

Solution. We know that

Q.8. Two spheres of the same meterial have radii 1 m and 4 m and temperatures 4000K and 2000K respectively. The energy radiated per second by the first sphere is greater than that by the second.

Ans. F

Solution. Energy radiated per second by the first sphere

Energy radiated per second by the second sphere