Heat and Thermodynamics · Physics · MHT CET

A metal rod cools at the rate of $$4{ }^{\circ} \mathrm{C} / \mathrm{min}$$ whon its temperature is $$90^{\circ} \mathrm{C}$$ and the rate of $$1{ }^{...

The molecular mass of a gas having r.m.s. speed four times as that of another gas having molecular mass 32 is

At constant temperature, increasing the pressure of a gas by $$5 \%$$ its volume will decrease by

The temperature of a gas is measure of

An ideal refrigerator has freezer at a temperature of $$-13^{\circ} \mathrm{C}$$. The coefficient of performance of the engine is 5. The temperature o...

The pressure and density of a diatomic gas $$\left(\gamma=\frac{7}{5}\right)$$ changes adiabatically from $$(\mathrm{P}, \rho)$$ to $$\left(\mathrm{P}...

A sphere and a cube, both of copper have equal volumes and are black. They are allowed to cool at same temperature and in same atmosphere. The ratio o...

A body is said to be opaque to the radiation if (a, r and t are coefficient of absorption, reflection and transmission respectively)

In a thermodynamic system, $$\Delta U$$ represents the increases in its internal energy and dW is the work done by the system then correct statement o...

The temperature of a gas is $$-68^{\circ} \mathrm{C}$$. To what temperature should it be heated, so that the r.m.s. velocity of the molecules be doubl...

A sphere, a cube and a thin circular plate all made of same material and having the same mass are heated to same temperature of $$200^{\circ} \mathrm{...

The efficiency of a heat engine is '$$\eta$$' and the coefficient of performance of a refrigerator is '$$\beta$$'. Then

A sample of oxygen gas and a sample of hydrogen gas both have the same mass, same volume and the same pressure. The ratio of their absolute temperatur...

The internal energy of a monoatomic ideal gas molecule is

A gas at pressure $$p_0$$ is contained in a vessel. If the masses of all the molecules are halved and their velocities are doubled, then the resulting...

For an adiabatic process, which one of the following is wrong statement?

Which one of the following is based on convection?

A carnot engine operates with source at $$227^{\circ} \mathrm{C}$$ and sink at $$27^{\circ} \mathrm{C}$$. If the source supplies $$50 \mathrm{~kJ}$$ o...

Which one of the following represents correctly the variation of volume (V) of an ideal gas with temperature $$(\mathrm{T})$$ under constant pressure ...

$$\mathrm{dQ}$$ is the heat energy supplied to an ideal gas under isochoric conditions. If $$\mathrm{dU}$$ and $$\mathrm{dW}$$ denote the change in in...

A black body at temperature $$127^{\circ} \mathrm{C}$$ radiates heat at the rate of $$5 \mathrm{~cal} / \mathrm{cm}^2 \mathrm{~s}$$. At a temperature ...

A Carnot engine has the same efficiency between (i) $$100 \mathrm{~K}$$ and $$600 \mathrm{~K}$$ and (ii) $$\mathrm{T} \mathrm{K}$$ and $$960 \mathrm{~...

For an ideal gas the density of the gas is $$\rho_0$$ when temperature and pressure of the gas are $$T_0$$ and $$P_0$$ respectively. When the temperat...

The temperature gradient in a rod of length $$75 \mathrm{~cm}$$ is $$40^{\circ} \mathrm{C} / \mathrm{m}$$. If the temperature of cooler end of the rod...

A black body radiates maximum energy at wavelength '$$\lambda$$' and its emissive power is '$$E$$'. Now due to a change in temperature of that body, i...

For polyatomic gases, the ratio of molar specific heat at constant pressure to constant volume is ( $$\mathrm{f}=$$ degrees of freedom)

Select the WRONG statement from the following. For an isothermal process

Compare the rate of loss of heat from a metal sphere at $$627^{\circ} \mathrm{C}$$ with the rate of loss of heat from the same sphere at $$327^{\circ}...

The volume of a metal block increases by $$0.225 \%$$ when its temperature is increased by $$30^{\circ} \mathrm{C}$$. Hence coefficient of linear expa...

A monoatomic ideal gas initially at temperature '$$\mathrm{T}_1$$' is enclosed in a cylinder fitted with massless, frictionless piston. By releasing t...

Let $$\gamma_1$$ be the ratio of molar specific heat at constant pressure and molar specific heat at constant volume of a monoatomic gas and $$\gamma_...

The molar specific heat of an ideal gas at constant pressure and constant volume is $$\mathrm{C}_{\mathrm{p}}$$ and $$\mathrm{C}_{\mathrm{v}}$$ respec...

A composite slab consists of two materials having coefficient of thermal conductivity $$\mathrm{K}$$ and $$2 \mathrm{~K}$$, thickness $$\mathrm{x}$$ a...

A black sphere has radius '$$R$$' whose rate of radiation is '$$E$$' at temperature '$$T$$'. If radius is made $$R / 3$$ and temperature '$$3 T$$', th...

A gas at normal temperature is suddenly compressed to one-fourth of its original volume. If $$\frac{\mathrm{C}_{\mathrm{p}}}{\mathrm{C}_{\mathrm{v}}}=...

About black body radiation, which of the following is the wrong statement?

For a gas, $$\frac{\mathrm{R}}{\mathrm{C}_{\mathrm{v}}}=0 \cdot 4$$, where $$\mathrm{R}$$ is universal gas constant and $$\mathrm{C}_{\mathrm{v}}$$ is...

Two bodies $$\mathrm{A}$$ and $$\mathrm{B}$$ at temperatures '$$\mathrm{T}_1$$' $$\mathrm{K}$$ and '$$\mathrm{T}_2$$' $$\mathrm{K}$$ respectively have...

If temperature of gas molecules is raised from $$127^{\circ} \mathrm{C}$$ to $$527^{\circ} \mathrm{C}$$, the ratio of r.m.s. speed of the molecules is...

According to Boyle's law, the product PV remains constant. The unit of $$\mathrm{PV}$$ is same as that of

The difference in length between two rods $$\mathrm{A}$$ and $$\mathrm{B}$$ is $$60 \mathrm{~cm}$$ at all temperatures. If $$\alpha_{\mathrm{A}}=18 \t...

An ideal gas expands adiabatically. $$(\gamma=1 \cdot 5)$$ To reduce the r.m.s. velocity of the molecules 3 times, the gas has to be expanded

Two spherical black bodies of radii '$$r_1$$' and '$$r_2$$' at temperature '$$\mathrm{T}_1$$' and '$$\mathrm{T}_2$$' respectively radiate power in the...

The rate of flow of heat through a metal rod with temperature difference $$40^{\circ} \mathrm{C}$$ is $$1600 \mathrm{~cal} / \mathrm{s}$$. The thermal...

If the temperature of a hot body is increased by $$50 \%$$, then the increase in the quantity of emitted heat radiation will be approximately

A monoatomic gas at pressure '$$\mathrm{P}$$', having volume '$$\mathrm{V}$$' expands isothermally to a volume '$$2 \mathrm{~V}$$' and then adiabatica...

A diatomic gas $$\left(\gamma=\frac{7}{5}\right)$$ is compressed adiabatically to volume $$\frac{V_i}{32}$$ where $$V_i$$ is its initial volume. The i...

If a gas is compressed isothermally then the r.m.s. velocity of the molecules

A black body radiates maximum energy at wavelength '$$\lambda$$' and its emissive power is 'E' Now due to change in temperature of that body, it radia...

Which of the following graphs between pressure (P) and volume (V) correctly shows isochoric changes? ...

A metal rod $$2 \mathrm{~m}$$ long increases in length by $$1.6 \mathrm{~mm}$$, when heated from $$0^{\circ} \mathrm{C}$$ to $$60^{\circ} \mathrm{C}$$...

We have a jar filled with gas characterized by parameters $$\mathrm{P}, \mathrm{V}, \mathrm{T}$$ and another jar B filled with gas having parameters $...

An insulated container contains a monoatomic gas of molar mass '$$\mathrm{m}$$'. The container is moving with velocity '$$\mathrm{V}$$'. If it is stop...

In a vessel, the ideal gas is at a pressure $$\mathrm{P}$$. If the mass of all the molecules is halved and their speed is doubled, then resultant pres...

The average force applied on the walls of a closed container depends on $$T^x$$ where $$T$$ is the temperature of an ideal gas. The value of '$$x$$' i...

A black body radiates maximum energy at wavelength '$$\lambda$$' and its emissive power is $$\mathrm{E}$$. Now due to change in temperature of that bo...

A Carnot engine with efficiency $$50 \%$$ takes heat from a source at $$600 \mathrm{~K}$$. To increase the efficiency to $$70 \%$$, keeping the temper...

A piece of metal at $$850 \mathrm{~K}$$ is dropped in to $$1 \mathrm{~kg}$$ water at $$300 \mathrm{~K}$$. If the equilibrium temperature of water is $...

Heat energy is incident on the surface at the rate of X J/min . If '$$a$$' and '$$r$$' represent coefficient of absorption and reflection respectively...

A sample of gas at temperature $$T$$ is adiabatically expanded to double its volume. The work done by the gas in the process is $$\left(\frac{\mathrm{...

An ideal gas in a container of volume 500 c.c. is at a pressure of $$2 \times 10^{+5} \mathrm{~N} / \mathrm{m}^2$$. The average kinetic energy of each...

A gas at N.T.P. is suddenly compressed to onefourth of its original volume. If $$\gamma=1.5$$, then the final pressure is

A gas is compressed at a constant pressure of $$50 \mathrm{~N} / \mathrm{m}^2$$ from a volume of $$10 \mathrm{~m}^3$$ to a volume of $$4 \mathrm{~m}^3...

The pressure exerted by an ideal gas at a particular temperature is directly proportional to

The side of a copper cube is $$1 \mathrm{~m}$$ at $$0^{\circ} \mathrm{C}$$. What will be the change in its volume, when it is heated to $$100^{\circ} ...

The temperature of an ideal gas is increased from $$27^{\circ} \mathrm{C}$$ to $$927^{\circ} \mathrm{C}$$. The r.m.s. speed of its molecules becomes...

A jar '$$\mathrm{P}$$' is filled with gas having pressure, volume and temperature $$\mathrm{P}, \mathrm{V}, \mathrm{T}$$ respectively. Another gas jar...

For a gas having '$$\mathrm{X}$$' degrees of freedom, '$$\gamma$$' is ($$\gamma=$$ ratio of specific heats $$=\mathrm{C_P / C_V}$$)

Two uniform brass rods $$A$$ and $$B$$ of length '$$l$$' and '$$2 l$$' and their radii '$$2 r$$' and '$$r$$' respectively are heated to same temperatu...

A gas at N.T.P. is suddenly compressed to $$\left(\frac{1}{4}\right)^{\text {th }}$$ of its original volume. The final pressure in (Given $$\gamma=$$ ...

In a thermodynamic process, there is no exchange of heat between the system and surroundings. Then the thermodynamic process is

According to kinetic theory of gases, which one of the following statements is wrong?

Three discs $$\mathrm{x}, \mathrm{y}$$ and $$\mathrm{z}$$ having radii $$2 \mathrm{~m}, 3 \mathrm{~m}$$ and $$6 \mathrm{~m}$$ respectively are coated ...

When the rms velocity of a gas is denoted by '$$v$$', which one of the following relations is true? ($$\mathrm{T}=$$ Absolute temperature of the gas.)...

A monoatomic gas $$\left(\gamma=\frac{5}{3}\right)$$ initially at $$27^{\circ} \mathrm{C}$$ having volume '$$\mathrm{V}$$' is suddenly compressed to o...

Two monatomic ideal gases A and B of molecular masses '$$m_1$$' and '$$m_2$$' respectively are enclosed in separate containers kept at the same temper...

The thermodynamic process in which no work is done on or by the gas is

Heat given to a body, which raises its temperature by 1ºC is known as

Which one of the following is NOT a correct expression for an ideal gas? [$$\mathrm{C_p}=$$ Molar specific heat of a gas at constant pressure, $$\math...

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...

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}...

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 ...

A monoatomic gas is suddenly compressed to $$(1 / 8)^{\text {th }}$$ of its initial volume adiabatically. The ratio of the final pressure to initial p...

A monoatomic ideal gas initially at temperature $$\mathrm{T}_1$$ is enclosed in a cylinder fitted with 8 frictionless piston. The gas is allowed to ex...

For a monoatomic gas, the work done at constant pressure is '$$\mathrm{W}$$' The heat supplied at constant volume for the same rise in temperature of ...

An ideal gas with pressure $$\mathrm{P}$$, volume $$\mathrm{V}$$ and temperature $$\mathrm{T}$$ is expanded isothermally to a volume $$2 \mathrm{~V}$$...

At what temperature does the average translational kinetic energy of a molecule in a gas becomes equal to kinetic energy of an electron accelerated fr...

The temperature difference between two sides of an iron plate, $$1.8 \mathrm{~cm}$$ thick is $$9^{\circ} \mathrm{C}$$. Heat is transmitted through the...

Internal energy of $$n_1$$ moles of hydrogen at temperature '$$T$$' is equal to internal energy of '$$n_2$$' moles of helium at temperature $$2 T$$, t...

For an ideal gas, $$R=\frac{2}{3} C_v$$. This suggests that the gas consists of molecules, which are [$$\mathrm{R}=$$ universal gas constant]

The rms speed of a gas molecule is '$$\mathrm{V}$$' at pressure '$$\mathrm{P}$$'. If the pressure is increased by two times, then the rms speed of the...

Equal volumes of two gases, having their densíties in the ratio of $$1: 16$$ exert equal pressures on the walls of two containers. The ratio of their ...

A cylindrical rod has temperatures '$$T_1$$' and '$$T_2$$' at its ends. The rate of flow of heat is '$$Q_1$$' cal $$\mathrm{s}^{-1}$$. If length and r...

The initial pressure and volume of a gas is '$$\mathrm{P}$$' and '$$\mathrm{V}$$' respectively. First by isothermal process gas is expanded to volume ...

If $$\mathrm{m}$$' represents the mass of each molecules of a gas and $$\mathrm{T}$$' its absolute temperature then the root mean square speed of the ...

An ideal gas at pressure '$$p$$' is adiabatically compressed so that its density becomes twice that of the initial. If $$\gamma=\frac{c_p}{c_v}=\frac{...

Which one of the following statements is wrong for an isobaric process?

For a perfectly black body, coefficient of emission is

Two rods of different metals have coefficients of linear expansion '$$\alpha_1$$' and '$$\alpha_2$$' respectvely. Their respective lengths are '$$\mat...

The temperature of a black body is increased by $$50 \%$$, then the percentage increase in the rate of radiation by the body is approximated

The emissive power of sphere of area $$0.04 \mathrm{~m}^2$$ is $$0.7 \mathrm{~k} \mathrm{~cal} \mathrm{~s}^{-1} \mathrm{~m}^{-2}$$. The amount of heat...

The rate of flow of heat through a copper rod with temperature difference $$28^{\circ} \mathrm{C}$$ is $$1400 \mathrm{~cal} \mathrm{~s}^{-1}$$. The th...

The change in internal energy of the mass of a gas, when the volume changes from '$$\mathrm{V}$$' to '$$2 \mathrm{~V}$$' at constant pressure 'P' is (...

If the pressure of an ideal gas is decreased by $$10 \%$$ isothermally, then its volume will

An ideal gas having molar mass '$$\mathrm{M}_0$$', has r.m.s. velocity 'V' at temperature 'T'. Then

An ideal gas at $$27^{\circ} \mathrm{C}$$ is compressed adiabatically to $$(8 / 27)$$ of its original volume. If ratio of specific heats, $$\gamma=5 /...

The translational kinetic energy of the molecules of a gas at absolute temperature (T) can be doubled

A polyatomic gas $$(\gamma=4 / 3)$$ is compressed to $$\left(\frac{1}{8}\right)^{\text {th }}$$ of its volume adiabatically. If its initial pressure i...

If the temperature of the sun is doubled, the rate of energy received by the earth will be increased by a factor

Which of the following statements is true? ($$\Delta \mathrm{U}=$$ increase in internal energy, $$\mathrm{dW}=$$ work done by the system)...

Let '$$\mathrm{W}_1$$' be the work done in blowing a soap bubble of radius '$$r$$' from soap solution at room temperature. The soap solution is now he...

A cylindrical rod is having temperatures $$\theta_1$$ and $$\theta_2$$ at its ends. The rate of heat flow is '$$Q$$' $$\mathrm{J}{\mathrm{s}}^{-1}$$. ...

For a gas molecule with 6 degrees of freedom, which one of the following relation between gas constant '$$\mathrm{R}$$' and molar specific heat '$$\ma...

What is the ratio of the velocity of sound in hydrogen $$\left(\gamma=\frac{7}{5}\right)$$ to that in helium $$\left(\gamma=\frac{5}{3}\right)$$ at th...

Equal volumes of two gases are kept in different containers having densities in the ratio 1 : 16. They exert equal pressures on the wall of their resp...

In thermodynamics, for an isochoric process, which one of the following statement is INCORRECT?

If '$$\mathrm{E}$$' is the kinetic energy per mole of an ideal gas and '$$\mathrm{T}$$' is the absolute temperature, then the universal gas constant i...

Two rods of same length and material are joined end to end. They transfer heat in 8 second. When they are joined in parallel they transfer same amount...

The molar specific heats of an ideal gas at constant pressure and volume are denoted by '$$\mathrm{C}_{\mathrm{p}}$$' and '$$C_v$$' respectively. If $...

The temperature difference bewtween two sides of metal plate, $$3 \mathrm{~cm}$$ thick is $$15^{\circ} \mathrm{C}$$. Heat is transmitted through plate...

A black body has maximum wavelength '$$\lambda_{\mathrm{m}}$$' at temperature $$2000 \mathrm{~K}$$. Its corresponding wavelength at temperature $$3000...

A monoatomic gas at pressure '$$\mathrm{P}$$' having volume '$$\mathrm{V}$$' expands isothermally to a volume $$2 \mathrm{~V}$$ and then adiabatically...

A black reactangular surface of area '$$a$$' emits energy '$$\mathrm{E}$$' per second at $$27^{\circ} \mathrm{C}$$. If length and breadth is reduced t...

Find the value of $$-$$197$$^\circ$$C temperature in Kelvin.

Which one of the following equations specifies an isobaric process? $$[Q=$$ heat supplied $$\Delta P, \Delta V$$ and $$\Delta T$$ are change in pressu...

A perfect gas of volume 10 litre n compressed isothermally to a volume of 1 litre. The rms speed of the molecules will

The relation obeyed by a perfect gas during an adiabatic process is $$\mathrm{PV}^{3 / 2}$$. The initial temperature of the gas is '$$\mathrm{T}$$'. W...

A black rectangular surface of area '$$\mathrm{A}$$' emits energy '$$\mathrm{E}$$' per second at $$27^{\circ} \mathrm{C}$$. If length and breadth is r...

A monoatomic gas is suddenly compressed to (1/8)th of its initial volume adiabatically. The ratio of the final pressure to initial pressure of the gas...

A conducting rod of length $$1 \mathrm{~m}$$ has area of cross-section $$10^{-3} \mathrm{~m}^2$$. One end is immersed in baiting water $$\left(100^{\c...

Two stars 'P' and 'Q' emit yellow and blue light respectively. The relation between their temperatures $$\left(\mathrm{T}_{\mathrm{P}}\right.$$ and $$...

A perfectly black body emits a radiation at temperature 'T$$_1$$' K. If it is to radiate at 16 times this power, its temperature 'T$$_2$$' K should be...

One mole of an ideal gas expands adiabatically at constant pressure such that its temperature $$T \propto {1 \over {\sqrt V }}$$. The value of $$\gamm...

On an imaginary linear scale of temperature (called 'W' scale) the freezing and boiling points of water are 39$$^\circ$$ W and 239$$^\circ$$ W respect...

Specific heats of an ideal gas at constant pressure and volume are denoted by $$\mathrm{C}_{\mathrm{p}}$$ and $$\mathrm{C}_{\mathrm{v}}$$ respectively...

For a monoatomic gas, work done at constant pressure is W. The heat supplied at constant volume for the same rise in temperature of the gas is

The root mean square velocity of molecules of a gas is $200 \mathrm{~m} / \mathrm{s}$. What will be the root mean square velocity of the molecules, if...

Two spherical black bodies of radius $$r_1$$ and $$r_2$$ with surface temperature $$T_1$$ and $$T_2$$ respectively, radiate same power, then $$r_1: r_...

A diatomic gas undergoes adiabatic change. Its pressure $$p$$ and temperature $$T$$ are related as $$p \propto T^x$$, where $$x$$ is

For a gas, $$\frac{R}{C_V}=0.4$$, where $$R$$ is universal gas constant and $$C_V$$ is the molar specific heat at constant volume. The gas is made up ...

A monoatomic gas of pressure $$p$$ having volume $$V$$ expands isothermally to a volume $$2V$$ and then adiabatically to a volume $$16 \mathrm{~V}$$. ...

The equation of state for 2 g of oxygen at a pressure ' $P$ ' and temperature ' $T$, when occupying a volume ' $V$ ' will be

The maximum wavelength of radiation emitted by a star is 289.8 nm . Then intensity of radiation for the star is (Given : Stefan's constant $=5.67 \tim...

If ' $C_P$ ' and ' $C_V$ ' are molar specific heats of an ideal gas at constant pressure and volume respectively. If ' $\lambda$ ' is the ratio of two...

A clock pendulum having coefficient of linear expansion. $\alpha=9 \times 10^{-7} /{ }^{\circ} \mathrm{C}^{-1}$ has a period of 0.5 s at $20^{\circ} \...

If $\alpha$ is the coefficient of performance of a refrigerator and ' $Q$ ' is heat released to the hot reservoir, then the heat extracted from the co...