NEET UG 2006 — Thermodynamics

The molar specific heat at constant pressure of an ideal gas is (7/2) $R$. The ratio of specific heat at constant pressure to that at constant volume is:

A black body at $1227^{\circ} \mathrm{C}$ emits radiations with maximum intensity at a wavelength of $5000 Å$. If the temperature of the body is increased by $1000^{\circ} \mathrm{C}$, the maximum intensity will be observed at:

A Carnot engine whose sink is at $300 \mathrm{~K}$ has an efficiency of $40 \%$. By how much should the temperature of source be increased so as to increase its efficiency by $50 \%$ of original efficiency?