Thermal properties of matter practice · Medium

A sample of an ideal gas occupies a volume $V$ at a pressure $P$ and absolute temperature $T,$ the mass of each molecule is $m.$ The expression for the density of gas is ($k = \;$ Boltzmaan’s constant)

Assertion (A): In laying down a railway track a small gap is left between the ends of the two consecutive rails
Reason (R): It is to allow for the linear expansion of rails in summer.

A copper ball of mass 100 g is at a temperature $T$. It is dropped in a copper calorimeter of mass 100 g, filled with 170 g of water at room temperature. Subsequently, the temperature of the system is found to be $75^\circ C$. $T$ is (Given, room temperature $= 30^\circ C$, specific heat of copper $= 0.1\,\mathrm{cal/g}^\circ C$)

(A): For higher temperature, the peak emision wavelength of a black body shifts to lower wavelengths.
(R): Peak emission wavelength of a black body is proportional to the fourth power of temperature.

If $\lambda_{{m}}$ denotes the wavelength at which the radiative emission from a black body at a temperature $T {~K}$ is maximum, then

Assertion (A): A tightly closed metal lid of a glass bottle can be opened more easily if it is put in hot water for some time.
Reason (R): The coefficient of expansion of metal lid is greater than that of glass.

In a composite rod, when two rods of different lengths and of the same area of cross-section are joined end to end, then if $K$ is the effective coefficient of thermal conductivity, $\frac{l_1+l_2}{K}$ is equal to:

(A): As temperature of a black body is raised, wavelength corresponding to maximum energy reduces.
(R): Higher temperature would mean higher energy and hence wavelength.

A glass full of hot milk is poured on the table. It begins to cool gradually. Because of:

$50 \mathrm{~g}$ ice at $0{ }^{\circ} \mathrm{C}$ in kept in an insulating vessel and $50 \mathrm{~g}$ water at $100{ }^{\circ} \mathrm{C}$ is mixed in it. Then the final temperature of the mixture is (neglect the heat loss)

Statement-I: A platinum wire can be sealed through glass. But a brass one cannot be sealed through glass.
Statement-II: Coefficient of linear expansion of platinum and that of brass have different values.

In the human body, the heart keeps the body temperature constant by the phenomena of

The temperature of a substance increases by ${27^0}C$. On the Kelvin scale this increase is equal to

Statement-I: A thick and thin metallic rods of same material heated through same rise of temperature then thermal stress is same.
Statement-II: Thermal stress is independent of area of cross section.

If 2 spheres of equal radius have same density same specific heat and both have same temperature $T$ and surrounding temperature is $T_s$. Then comment on:

(i) Rate of heat loss

(ii) Rate of cooling.

A metallic sphere cools from $50{}^\mathrm{o}\mathrm{C}\,\mathrm{to}\,\,\,\mathrm{4}{\mathrm{0}^\mathrm{o}}\mathrm{C}\,\,\,\mathrm{in\,\, 300}\,\mathrm{s}\mathrm{.}$ If atmospheric temperature around is ${20^o}C,$ then the sphere’s temperature after the next 5 min will be close to

Two liquids $A$ and $B$ are at $30^\circ C\,\,\mathrm{and}\,\,20^\circ C$ respectively. When they are mixed in equal masses the temperature of the mixture is found to be $26^\circ C.$ The ratio of specific heats is

Statement-1: Specific heat capacity is the cause of formation of land and sea breeze.
Statement-2: The specific heat of water is more than that of land.

Statement-I: Platinum is used to fuse into glass tube.
Statement-II: Both platinum and glass have almost same values of coefficient of linear expansion.

On investigation of light from three different stars A, B and C, it was found that in the spectrum of A the intensity of red colour is maximum, in B the intensity of blue colour is maximum and in C the intensity of yellow colour is maximum. From these observations it can be concluded that

Under constant temperature, graph between $P$ and $1/V$ is

Assertion (A): Ideal gas molecules possess potential energy.
Reason (R): There exists a force of attraction between molecules of ideal gas.

Two metal strips that constitute a thermostat must necessarily differ in their

The temperature at which the vapour pressure of a liquid becomes equals to the external (atmospheric) pressure is its

Statement-I: When hot water is poured in a thick glass tumbler then the tumbler breaks.
Statement-II: Glass is a bad conductor of heat

$10 \mathrm{~gm}$ of ice at $-20^{\circ} \mathrm{C}$ is dropped into a calorimeter containing $10 \mathrm{~gm}$ of water at $10^{\circ} \mathrm{C}$. The specific heat of water is twice that of ice. Neglect heat capacity of the calorimeter. When equilibrium is reached, the calorimeter will contain

There is formation of layer of snow $x\,\,cm$ thick on water, when the temperature of air is $- {0^0}C$ (less than freezing point). The thickness of layer increases from $x$ to $y$ in the time $t$, then the value of $t$ is given by

Statement A: Woolen clothes keep the body warm in winter
Statement B: Air is a bad conductor of heat

Triple Point of Water is

A metallic ball has spherical cavity at its centre. If the ball is heated, what happens to the cavity?