Thermal Properties of Matter

Assertion : Coefficient of thermal conductivity of a metal rod is a function of length of the rod. Reason : Longer the rod, larger is the amount of heat conducted.

Calculate radiation power for sphere whose temperature is $227^{\circ} \mathrm{C}$, radius $2 \mathrm{~m}$ and emissivity 0.8 ?

A body initially at $80^{\circ} \mathrm{C}$ cools to $64^{\circ} \mathrm{C}$ in $5 \mathrm{~min}$ and to $52^{\circ} \mathrm{C}$ in $10 \mathrm{~min}$. The temperature of the surrounding is

Assertion : The specific heat of a gas in an adiabatic process is zero and in an isothermal process is infinite. Reason : Specific heat of gas is directly proportional to change of heat in system and inversely…

The temperature of a body is increased from $-73^{\circ} \mathrm{C}$ to $327^{\circ} \mathrm{C}$. Then the ratio of emissive power is

Assertion : The conductivity of an electrolyte is very low as compared to a metal at room temperature. Reason : The number density of free ions in electrolyte is much smaller as compared to number density of free…

Assertion : A hollow metallic closed container with small opening maintained at a high temperature can act as a source of black body radiation. Reason : All metals act as black body radiator.

Assertion: UV radiation causes photo dissociation of ozone into $\mathrm{O}_2$ and $\mathrm{O}$, thus causing damage to the stratospheric ozone layer. Reason : Ozone hole is resulting in global warming and climate…

A copper ball $2 \mathrm{~cm}$ in radius is heated in a furnace to $327^{\circ} \mathrm{C}$. If its emissivity is 0.3 , at what rate does it radiate energy?

If $10 \mathrm{~g}$ oficeis added to $40 \mathrm{~g}$ of water at $15^{\circ} \mathrm{C}$, then the temperature ofthemixture is (specificheat of water $=4.2 \times 10^3 \mathrm{~J} \mathrm{~kg}^{-1} \mathrm{~K}^{-1}$,…

$1 \mathrm{~g}$ of steam is sent into $1 \mathrm{~g}$ of ice. At thermal equilibrium, the resultant temperature of mixture is

Assertion : Maximum air flow due to convection does not occur at the north pole but it occurs at $30^{\circ} \mathrm{N}$Reason : There is maximum temperature difference between equator and $30^{\circ} \mathrm{N}$