The molecular masses of helium and oxygen are 4 and 32 respectively. The ratio of r.m.s. speed of helium at 327$$^\circ$$ to r.m.s. speed of oxygen at 27$$^\circ$$ will be

Which one of the following p-V diagram is correct for an isochoric process:

Assume that for solar radiation, surface temperature of the sun is $$6000 \mathrm{~K}$$. If Wien's constant 'b' is $$2.897 \times 10^{-3} \mathrm{~mK}$$, the value of maximum wavelength will be

A metal sphere cools at the rate of $$1.5^{\circ} \mathrm{C} / \mathrm{min}$$ when its temperature is $$80^{\circ} \mathrm{C}$$. At what rate will it cool when its temperature falls to $$50^{\circ} \mathrm{C}$$. [Temperature of surrounding is $$30^{\circ} \mathrm{C}$$]