The number of rotational degrees of freedom of a diatomic molecule
A metal tape is calibrated at $$25^{\circ} \mathrm{C}$$. On a cold day when the temperature is $$-15^{\circ} \mathrm{C}$$, the percentage error in the measurement of length is
(Coefficient of linear expansion of metal $$=1 \times 10^{-5}{ }^{\circ} \mathrm{C}^{-1}$$)
A gas is expanded from an initial state to a final state along a path on a $$p$$-$$V$$ diagram. The path consists of (i) an isothermal expansion of work 50 J , (ii) an adiabatic expansion and (iii) an isothermal expansion of work 20 J . If the internal energy of gas is changed by $$-$$30 J , then the work done by gas during adiabatic expansion is
The temperature of the sink of a Carnot engine is 250 K . In order to increase the efficiency of the Carnot engine from $$25 \%$$ to $$50 \%$$, the temperature of the sink should be increased by