The equation of state of n moles of an ideal gas is PV = nRT, where R is a constant. The SI unit for R is


Correct option is

J K – 1 mol – 1


Since R = PV/nT, the SI unit of R is




Two rods of different materials having coefficients of thermal expansion  and Young’s modulii Y1Y2 respectively are fixed between two rigid massive walls. The rods are heated such that they undergo the same increase in temperature. There is no bending of the rods. If  the thermal stresses developed in the two rods are equal provided Y1 : Y2 is equal to:


The water equivalent of a copper calorimeter is 4.5 g. If the specific heat of copper is 0.09 cal.g–1oC–1 the


A slab of stone of area 0.34 m2 and thickness 10 cm is exposed on the lower face to steam at 100oC. A block of ice at 0oC rests on the upper face of the slab. In one hour, 3.6 kg of ice is melted. Assume that the heat loss from the sides is negligible. The latent heat of fusion of ice is  What is the thermal conductivity of the stone in units of Js–1m–1oC–1?


An ice-box is made of wood 1.75 cm thick, lined inside with cork 2 cm thick. If the temperature of the inner surface of the cork is steady at 0oC and that of the outer surface is steady at 12oC, what is the temperature of the surface? The thermal conductivity of wood is 5 times that of cork.



The tungsten filament of an electric lamp has a surface area A and a power rating P. if the emissivity of the filament is  is Stefan’s constant, the steady temperature of the filament will be


What are the dimensions of Stefan’s constant?


Each square meter of sun’s surface radiates energy at the rate of . Assuming that Stefan’s law applies to the radiation, the temperature of sun’s surface is (Stefan’s constant )


Experimental investigations show that the intensity of the solar radiation is maximum for a wavelength 4750  in the visible region. If the surface temperature of the sun is 6000 K, what is the value of the Wien’s constantb?


The specific heat of helium at constant volume is 12.6 J mol–1K–1. What is the specific of hydrogen at constant volume in J mol–1K–1? Assume that the temperature of the gas is moderate.


A thin copper wire of length L increases its length by 1% when heated from temperature T1 to T2. What is the percentage change in area when a thin copper plate having dimensions  is heated from T1 toT2?