Thermal properties of matter practice · Medium

It is known that wax contracts on solidification. If molten wax is taken in a large vessel and it is allowed to cool slowly, then

When a metal ring having some gap is heated
a) Length of gap increases
b) Radius of the ring decreases
c) The angle subtended by the gap at the centre remains same
d) Length of gap decreases

A body takes 5 minutes to cool down from $50^{\circ}$ to $40^{\circ} \mathrm{C}$ in surrounding of temperature $20^{\circ}$ C. Then the time taken by the same body to cool down from $40^{\circ} \mathrm{C}$ to $30^{\circ} \mathrm{C}$ in a surrounding of temperature $10^{\circ} \mathrm{C}$ is (Assuming Newton's law of cooling is valid)

The temperature of a body falls from $40^{\circ} \mathrm{C}$ to $36^{\circ} \mathrm{C}$ in 5 minutes when placed in a surrounding of constant temperature $16^{\circ} \mathrm{C}$. Find the time taken for the temperature of the body to become $32^{\circ} \mathrm{C}$.

When the door of a refrigerator is kept open then the room temperature

In a mercury thermometer the ice point (lower fixed point) is marked as ${10^0}$ and the steam point (upper fixed point) is marked as ${130^0}$. At ${40^0}C$ temperature, what will this thermometer read

The rate of cooling at 600 K, if surrounding temperature is 300 K is $R$. The rate of cooling at 900 K is

Assertion: A temperature change which increases the length of a steel rod by $1 \%$ will increase its volume by $3 \%.$
Reason: The coefficient 1 volume expansion is nearly three times the coefficient of linear expansion.

A black body at ${227^0}C$ radiates heat at the rate of $7\,\,Cal/c{m^2}s$ . At a temperature of ${727^0}C$ , the rate of heat radiated in the same units will be

A bucket full of hot water is kept in a room and it cools from $75^\circ \,C$ to $70^\circ \,C$ in ${T_1}$ minutes, from $70^\circ \,C$ to $65^\circ \,C$ in ${T_2}$ minutes and from $65^\circ \,C$ to $60^\circ \,C$ in ${T_3}$ minutes. Then

Assertion: It is hotter over the top of a fire than at the same distance on the sides.
Reason: In the upward direction, the heat propagates through convection.

Which is the following is more close to a black body?

The property of water which is a boon to aquatic animals and plants is:

In a pressure cooker, cooking is faster because the increase of vapour pressure

For one gram mol of a gas, the value of R in the equation $PV = RT$ is nearly

A sample of ${O_2}$ gas and a sample of ${H_2}$ gas both have the same mass, the same volume and the same pressure. Assuming to be perfect gases, the ratio of the temperature of ${O_2}$ gas to the temperature of the ${H_2}$ gas is

When vapour condenses into liquid

A barometer with a brass scale correct at $0^\circ C$ reads 70 cm of mercury on a day when the air temperature is $40^\circ C$. The correct reading at $0^\circ C$ is [Coefficient of real expansion of mercury is $0.00018/^\circ C$ and the coefficient of linear expansion of brass is $0.000018/^\circ C$ ]

A body temperature is change $90^{\circ} \mathrm{C}$ to $60^{\circ} \mathrm{C}$ in 5 minutes then find out the taken time when its is change $60^{\circ} \mathrm{C}$ to $30^{\circ} \mathrm{C}$ when temperature of surrounding is $20^{\circ} \mathrm{C}$.

Select correct statement related to heat

Assertion: A good absorber is a good emitter.
Reason: For a substance, absorbance is equal to emissivity.

In two same dimensional vessels same amount and same temperature ice is filled. If in both vessels complete ice is melt in 20 $\mathrm{min}$ and $50 \mathrm{~min}$ then find out the ratio of thermal conductivity of both vessels.

A piece of blue glass heated to a high temperature and a piece of red glass at room temperature, are taken inside a dimly lit room then

In which mode of transmission, the heat waves travel along straight line with the speed of light?

Mercury is often used in clinical thermometers. Which one of the following properties of mercury is not a reason for this?

Four rods of silver, copper, brass and wood are of same shape. They are heated together after wrapping a paper on it, the paper will burn first on

Critical temperature can be defined as the

Good absorbers of heat are

Two identical plates of different metals are joined to form a single plate whose thickness is double the thickness of each plate. If the coefficients of conductivity of each plate are 2 and 3 respectively, then the conductivity of composite plate will be

At NTP water boils at ${100^0}C$. Deep down the mine, water will boil at a temperature