At which temperature the r.m.s. velocity of a hydrogen molecule equal to that of an oxygen molecule at $$47^{\circ} \mathrm{C}$$ ?

The temperature of a gas having $$2.0 \times 10^{25}$$ molecules per cubic meter at $$1.38 \mathrm{~atm}$$ (Given, $$\mathrm{k}=1.38 \times 10^{-23} \mathrm{JK}^{-1}$$) is :

$$N$$ moles of a polyatomic gas $$(f=6)$$ must be mixed with two moles of a monoatomic gas so that the mixture behaves as a diatomic gas. The value of $$N$$ is :

A thermodynamic system is taken from an original state $$\mathrm{A}$$ to an intermediate state $$B$$ by a linear process as shown in the figure. It's volume is then reduced to the original value from $$\mathrm{B}$$ to $$\mathrm{C}$$ by an isobaric process. The total work done by the gas from $$A$$ to $$B$$ and $$B$$ to $$C$$ would be :