MCQ Questions for Class 11 Engineering Physics Thermal Properties Of Matter Quiz 13

The pressure of an ideal gas veries according to the law

$P=P_{0}-AV^{2}$ where

$P_{0}$ and A are positive constants. What is the highest temperature that can be attained by the gas?

0%
$\dfrac{P_{0}}{nR}\sqrt{\dfrac{P_{0}}{A}}$
0%
$\dfrac{P_{0}}{nR}\sqrt{\dfrac{P_{0}}{2A}}$
0%
$\dfrac{2P_{0}}{nR}\sqrt{\dfrac{P_{0}}{2A}}$
0%
$\dfrac{2P_{0}}{3nR}\sqrt{\dfrac{P_{0}}{3A}}$

Radiation emitted from a radioactive element, of half life period of

$30$ min, are measured by a Geigar - Mullar counter. The count rate of the sample reduces to

$5$ disintegrations /sec. in

$2hrs$ . then the initial count rate in disintegration/sec is :-

0%
$805$
0%
$200$
0%
$250$
0%
$40$

Explanation

[A]

Half life = 30 mins

N = 5 / sec

Time = 120 min

$\begin{array}{l} \frac { N }{ { { N_{ 0 } } } } ={ \left( { \frac { 1 }{ 2 } } \right) ^{ \frac { { Time } }{ { half\, \, life } } } }={ \left( { \frac { 1 }{ 2 } } \right) ^{ \frac { { 120 } }{ { 30 } } } }=\frac { 1 }{ { 16 } } \\ { N_{ 0 } }=16\times N={ 805^{ -1 } } \end{array}$

Two metallic sphere

$S_1$ and

$S_2$ are made of the same material and have got identical surface finish.The mass of

$S_1$ is thrice that of

$S_2$ .Both the sphere are heated to the same high temperature and placed in the same room having lower temperature but are thermally insulated from each other.The ratio of the initial rate of cooling of

$S_1$ to that

$S_2$ is :

0%
$\dfrac{1}{3}$
0%
$\dfrac{1}{\sqrt{3}}$
0%
$\dfrac{\sqrt{3}}{1}$
0%
$\left(\dfrac{1}{3}\right)^{\dfrac{1}{3}}$

Consider the situation as shown in fig. Calculate the amount of heat flowing per second through a cross section of the bent part, if the total heat taken out per second from the end at

$100^{o}C$ is

$130\ J$ .

0%
$130\ J$
0%
$60\ J$
0%
$70\ J$
0%
$80\ J$

A metre scale made of steel is calibrated at

${20^ \circ C}$ to give correct reading. Find the distance between

$50cm$ mark and

$51cm$ mark if the scale is used at

${10^ \circ C}$ . Coefficient of linear expansion of steel is

$1.1 \times {10^{ - 5o}}{C^{ - 1}}$ .

0%
$\text{1.000 11 cm}$
0%
$\text{1.11 cm}$
0%
$\text{0.999m}$
0%
$\text{1.01 m}$

Explanation

$\begin{array}{l} { l_{ s } }=l\left( { 1-d\, steal\Delta T } \right) \\ =1\left( { 1-1.1\times { { 10 }^{ -5 } }\times 10 } \right) \\ =0.9998\, m\\ Hence,\, option\, C\, is\, the\, correct\, answer. \end{array}$

Two closed containers of equal volume filled with air at pressure

$P_{0}$ and temperature

$T_{0}$ . Both are connected by narrow tube. If one of the container is maintained at temperature

$T_{0}$ and another at temperature T, then new pressure in the containers will be

0%
$\dfrac{2P_{0}T}{T+T_{0}}$
0%
$\dfrac{P_{0}T}{T+T_{0}}$
0%
$\dfrac{P_{0}T}{2(T+T_{0}})$
0%
$\dfrac{T+T_{0}}{P_{0}}$

A hot body is placed in cooler surrounding. When the hot body temperature

$75^{\circ}C$ , the rate of cooling is

$4^{\circ}C/min$ . When it is

$55^{\circ}C$ , the rate of cooling is

$2^{\circ}C/min$ . The temperature of the surroundings is

0%
$20^{\circ}C$
0%
$25^{\circ}C$
0%
$30^{\circ}C$
0%
$35^{\circ}C$

Explanation

We know that,

cooling rate is directly proportional to difference of temperature of body and temperature of surroundings

$\dfrac { d\theta }{ dt } \propto ({ \theta }_{ t }-{ \theta }_{ s })\\$

$\dfrac { d\theta }{ dt } =k({ \theta }_{ t }-{ \theta }_{ s })$ --------------------------(1)

Given,

$At\quad { 75 }^{ \circ }C\quad ,\dfrac { d\theta }{ dt } ={ 4 }^{ \circ }C/min$

And

$At\quad { 55 }^{ \circ }C\quad ,\dfrac { d\theta }{ dt } ={ 2 }^{ \circ }C/min$

Substitute all value in equation(1)

$4=k(75-{ \theta }_{ s })$ ---------------------------------------(2)

And

$2=k(55-{ \theta }_{ s })$ ----------------------------------------(3)

By Dividing both the above equation we will get

$\dfrac { 4 }{ 2 } =\dfrac { k(75-{ \theta }_{ s }) }{ k(55-{ \theta }_{ s }) }$

$\ { 2 } =\dfrac { (75-{ \theta }_{ s }) }{ (55-{ \theta }_{ s }) }$

$2(55-{ \theta }_{ s })=(75-{ \theta }_{ s })$

$110-{ 2\theta }_{ s }=75-{ \theta }_{ s }$

$110-75=2{ \theta }_{ s }-{ \theta }_{ s }$

${ \theta }_{ s }=35$

Hence, Temperature of surroundings is 35 degree celcious.Hence, Option (D) is correct option.

Compare rate of radiation of metal sphere at

$627^0C$ annd

$327^0C$ .

0%
0.7 : 1
0%
3 : 1
0%
63 : 1
0%
5.063 : 1

Explanation

According to stafan's Law

$E=k{ T }^{ 4 }$

Then,

$\dfrac { { E }_{ 1 } }{ { E }_{ 2 } } ={ \left( \dfrac { { T }_{ 1 } }{ { T }_{ 2 } } \right) }^{ 4 }$

$\dfrac { { E }_{ 1 } }{ { E }_{ 2 } } ={ \left( \dfrac { 627+273 }{ 327+273 } \right) }^{ 4 }$

$\dfrac { { E }_{ 1 } }{ { E }_{ 2 } } ={ \left( \dfrac { 900 }{ 600 } \right) }^{ 4 }$

$\dfrac { { E }_{ 1 } }{ { E }_{ 2 } } ={ \left( \dfrac { 3 }{ 2 } \right) }^{ 4 }$

$\dfrac { { E }_{ 1 } }{ { E }_{ 2 } } ={ \left( \dfrac { 1.5 }{ 1 } \right) }^{ 4 }$

$\dfrac { { E }_{ 1 } }{ { E }_{ 2 } } =\dfrac { { 1.5 }^{ 4 } }{ 1 }$

$\dfrac { { E }_{ 1 } }{ { E }_{ 2 } } =\dfrac { 5.0625 }{ 1 }$

Hence, option (D) is correct Option.

In the given figure, if the heat flowing through the

$5 \Omega$ resistance is 10 calorie then how much heat is flowing through the

$4\Omega$ resistance ?

0%
$1$ calorie
0%
$2$ calorie
0%
$3$ calorie
0%
$4$ calorie

Two rods with the same dimensions have thermal conductivity in the ratio

$1:\ 2$ . They are arranged between heat reservoirs with the same temperature difference, in two different configurations, in two different configurations.

$A\ and\ B$ . The rates of heat flow in

$A\ and\ B$ are

$I_{A}\ and\ I_{B}$ respectively. The ratio

$\dfrac{I_{A}}{I_{B}}$ is equal to

0%
$1:\ 2$
0%
$1:\ 3$
0%
$2:\ 5$
0%
$2:\ 9$

Two bodies

$A$ and

$B$ having equal surface areas are maintained at temperatures

$10 ^ { \circ } \mathrm { C }$ and

$20 ^ { \circ } \mathrm { C }$ . The thermal radiation emitted in a given time by

$A$ and

$B$ are in the ratio

0%
$1 : 1.15$
0%
$1 : 2$
0%
$1 : 4$
0%
$1 : 16$

Two rods A and B of same length and radius are joined together. the thermal conductivity of A and B are

$2K$ and

$K$ . Under steady state conditions, if the temperature difference between the open ends of A and B is

$36^{\circ}C$ , the temperature difference across 'A' is:

0%
$12^{\circ}C$
0%
$18^{\circ}C$
0%
$24^{\circ}C$
0%
$9^{\circ}C$

Two identical square rods of metal are welded end to end as shown in figure (a).

$20$ calories of heat flows through it in

$4$ minutes. if the rods are welded as shown in figure (b), the same amount of heat will flow through the rods in

0%
$1$ minute
0%
$2$ minutes
0%
$4$ minutes
0%
$16$ minutes

Explanation

The rate at which the heat is developed is given by

$\dfrac{dQ}{dt} = \dfrac{KA \delta T }{L}$

$\dfrac{dQ}{dt} = \dfrac{KA \delta (T_1-T_2) }{2x}$

Now , we have

$\dfrac{dQ}{dt} = \dfrac{2 KA \delta T }{x}$

Therefore by solving above we have , t=2 minutes

In a container of negligible heat capacity

$100 gm$ of a liquid at

$20 ^ { \circ } \mathrm { C }$ is heated. Specific heat of the liquid varies with temperature given as

$s = ( 100 T + 500 ) J / k g ^ { \circ } C$ where

$T$ is in

$^{ \circ }C$ . Find the amount of heat required to raise the temperature of the liquid to

$40 ^ { \circ } \mathrm { C }$

0%
$5000 J$
0%
$6000 J$
0%
$7000 J$
0%
$8000 J$

A copper block A of mass 500 gm and

$S_p$ heat 0.1 cal/gm/

$^ { \circ } C$ is heated from

$30 ^ { \circ } C \text { to } 40 ^ { \circ } C$ . Another identical copper block B of same mass is heated from

$35 ^ { \circ } C \text { to } 40 ^ { \circ } C$ . The ratio of their thermal capacities is:

0%
1 : 2
0%
2 : 1
0%
1 : 1
0%
1 : 4

A copper bar

$10\ cm$ long has its ends passed against copper tanks at

$0^{o}C$ and

$100^{o}C$ . The ends are separated by layers of dust

$0.1\ mm$ thick. If conductivity of dust is

$0.001$ times that of copper, the temperature of end

$P$ and

$Q$ of bar are [Take rate of flow of heat constant from

$P$ to

$Q$ ]

0%
$33.3^{o}C$ and $66.7^{o}C$
0%
$66.7^{o}C$ and $33.3^{o}C$
0%
$75^{o}C$ and $25^{o}C$
0%
$60^{o}C$ and $40^{o}C$

One end of a thermally insulated rod is kept at a temperature

$T_1$ and the other at

$T_2$ . The rod is composed of two sections of lengths

$L_1$ and

$L_2$ and thermal conductivities

$k_1$ and

$k_2$ respectively. The temperature at the interface of the sections is

0%
$\displaystyle \frac{(K_2L_2T_1+K_1L_1T_2)}{(K_1L_1+K_2L_2)}$
0%
$\displaystyle \frac{(K_2L_1T_1+K_1L_2T_2)}{(K_2L_1+K_1L_2)}$
0%
$\displaystyle \frac{(K_1L_2T_1+K_2L_1T_2)}{(K_1L_2+K_2L_1)}$
0%
$\displaystyle \frac{(K_1L_1T_1+K_2L_2T_2)}{(K_1L_1+K_2L_2)}$

The pressure of the gas contained in a closed vessel is increased by

$0.4\%$ when heated by

$1^oC$ . The initial temperature of the gas must be

0%
$1250 K$
0%
$250 K$
0%
$2500 K$
0%
$25^oC$

When is the temperature at its peak? what is its value then?

0%
$4 hrs,106.4^{o}F$
0%
$3 hrs,102.4^{o}F$
0%
$2 hrs,104.4^{o}F$
0%
$1 hrs,98^{o}F$

A beaker of height H is made up of a material whose coefficient of linear thermal expansion is 3

$\alpha$ . It is filled up to the brim by a liquid whose coefficient of thermal expansion is

$\alpha$ . If now the beaker along with its contents is uniformly heated through a small temperature T the level of liquid will reduce by (given

$\alpha <<1$ .)

0%
$\alpha TH$
0%
$3\alpha TH$
0%
$9\alpha TH$
0%
$6\alpha TH$

A crystal has a coefficient of expansion

$1.3\times 10^{-8}$ in one direction and

$2.31\times 10^{-7}$ in every direction at right angles to it. Then the cubical coefficient of expansion is :

0%
$4.62\times 10^{-7}$
0%
$2.44\times 10^{-7}$
0%
$4.75\times 10^{-7}$
0%
$2.57\times 10^{-7}$

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

0%
125%
0%
200%
0%
300%
0%
400%

Explanation

let us assume initial Temperature $T_1=T$ then final will be

$T_2=\dfrac{50}{100}T+T=\dfrac{150}{100}T=\dfrac{15}{10}T$

energy radiated

$e_1=\sigma A T_1^4\quad \left(1\right)$

$e_2=\sigma A T_2^4\quad \left(2\right)$

$\%$ increase in radiation

$=\dfrac{e_2-e_1}{e_1}\times 100$

$=\dfrac{\sigma A T_2^4-\sigma A T_1^4}{\sigma A T_1^4}\times 100$

$\dfrac{\left(\dfrac{15}{10}T\right)^4-T^4}{T^4}\times 100$

$\dfrac{15^4-10^4}{10^4}\times 10^2$

$\dfrac{50625-10000}{10^2}$

$=406.25$

$\approx 400\%$

Hence

$(d)$ option is correct.

When a body is placed in surrounding at a constant temperature of

$20^\circ$ C, and heated by a

$10$ -W, heater, its temperature remains constant at

$40^\circ$ C. If the temperature

0%
$3000$ J
0%
$3600$ J
0%
$4500$ J
0%
$5400$ J

In on heating liquid through

${80}^{o}C$ , the mass expelled is (1/100)th of mass still remaining, the coefficient of apparent expansion of liquid is:

0%
$1.25\times{10}^{-4}/^{o}C$
0%
$12.5\times{10}^{-4}/^{o}C$
0%
$1.25\times{10}^{-5}/^{o}C$
0%
None of these

Find the temperature at which the thermometer reads correctly?

0%
60C
0%
40C
0%
50C
0%
55C

Two metal cubes A and B of same size are arranged as shown in the figure. The extreme ends of the combination are maintained at the indicated temperatures. The arrangement is thermally insulated. The coefficients of thermal conductivity of A and B are 300

$W/m^0C$ and 200

$W/m^0C$ , respectively. After steady state is reached, the temperature of the interface will be

0%
$45^0C$
0%
$90^0C$
0%
$30^0C$
0%
$60^0C$

Explanation

Temperature of interface is given by :

$T=\dfrac{K_1\theta_1+K_2\theta_2}{K_1+K_2}$

$=\dfrac{300 \times 100+200 \times 0}{300+200}=60 ^\circ C$

Radius of the sun is

$7\times { 10 }^{ 8 }m$ and the energy radiated by it is

$38\times { 10 }^{ 28 }W$ . Calculate the magnitude of energy propagation poynting vector (i.e., energy flowing per second per unit area) on the surface of sun:-

0%
$6.17\times { 10 }^{ 8 }W/{ m }^{ 2 }$
0%
$6.17\times { 10 }^{ 9 }W/{ m }^{ 2 }$
0%
$6.17\times { 10 }^{ 10 }W/{ m }^{ 2 }$
0%
$6.17\times { 10 }^{ 11 }W/{ m }^{ 2 }$

Three rods AB,BC and AC having thermal resistances of 10 units, 10 units and 20 units, respectively, are connected as shown in the figure. Ends A and C are maintained at constant temperatures of

$100^{ \circ }C$ and

$0^{ \circ }C,$ respectively. The rate at which the heat is crossing junction B is:

0%
5 units
0%
10 units
0%
20 units
0%
7.5 units

One end of a 0.25 m long metal bar is in steam and the other end is in contact with ice. If 12 g of ice melts per minute , What is the thermal conductivity of the metal ? Given cross-section of the bar

$=5\times { 10 }^{ -4 }{ m }^{ 2 }$ and latent heat of ice is 80 cal/g

0%
$80cal/s-{ m- }^{ \circ }$ C
0%
$90cal/s-{ m- }^{ \circ }$ C
0%
$70cal/s-{ m- }^{ \circ }$ C
0%
$60cal/s-{ m- }^{ \circ }$ C

If the system takes 100 cal. heat, and releases 80 cal to sink, if source temperature is

$127^oC$ find the sink temperature :-

0%
$47^oC$
0%
$127^oC$
0%
$67^oC$
0%
$107^oC$

The value of universal gas constant is

$R=8.3$ J/K - mol. The value of

$R$ in atmosphere litre per kelvin mol

0%
$8.12$
0%
$0.00812$
0%
$81.2$
0%
$0.082$

A long mercury glass tube with a uniform capillary bore has in it a thread of mercury which is

$1m$ long at

$0^\circ C$ . What will be its length at

$100^\circ C$ is the real coefficient of expansion of mercury is

$0.000182^\circ C^{-1}$ and coefficient of cubical expansion of glass equal to

$0.000025^\circ C^{-1}$ .

0%
$0.516\ m$
0%
$1.016\ m$
0%
$1.516\ m$
0%
$2.016\ m$

At what temperature is the r.m.s velocity of a hydrogen molecule equal to that of an oxygen molecule at

${47}^{o}C$ ?

0%
$80K$
0%
$-73K$
0%
$3K$
0%
$20K$

A glass bottle of capacity

$50\ cc$ at

$0^\circ C$ is filled with paraffin at

$15^\circ C$ . Given that the density of paraffin at

$0^\circ C$ is

$0.82\ g/cc$ , coefficient of expansion of paraffin is

$0.0009^\circ C$ and coefficient of linear expansion is

$0.000009^\circ C$ , the mass of paraffin in the bottle is:-

0%
$40.5\ g$
0%
$54.0\ g$
0%
$50.4\ g$
0%
$5.04\ g$

Two metal spheres have radii r and 2r and they emit thermal radiation with maximum intensities at wavelengths

$\lambda$ and

$2\lambda$ respectively. The respective ratio of the radiant energy emitted by them per second will be

0%
4 : 1
0%
1 : 4
0%
16 : 1
0%
8 : 1

$4.0g$ of a gas occupies

$22.4 litres$ at

$NTP$ . The specific heat capacity of the gas at constant volume is

$5.0{ JK }^{ -1 }{mol }^{ -1 }$ . If the speed of sound in this gas at NTP is

$952ms^{-1}$ , then the heat capacity at constant pressure is(Take gas constant

$R= 8.3{ JK }^{ -1 }{mol }^{ -1 }$ )

0%
$8.5{ JK }^{ -1 }{mol }^{ -1 }$
0%
$8.0{ JK }^{ -1 }{mol }^{ -1 }$
0%
$7.5{ JK }^{ -1 }{mol }^{ -1 }$
0%
$7.0{ JK }^{ -1 }{mol }^{ -1 }$

Three closed vessels A, B and C are at the same temperature T and contain gases which obey the Maxwellian distribution of velocities, Vessel A contains only

${ O }_{ 2 }$ B only

${ N }_{ 2 }$ and C a mixture of equal quantities of

${ O }_{ 2 }$ and

${ N }_{ 2 }$ If the average speed of the

${ O }_{ 2 }$ molecules in vessel A is

${ V }_{ 1 }$ , that of

$N_{ 2 }$ molecules in vessel B is

$V_{ 2 }$ the average speed of the

$O_{ 2 }$ molecules in vessel C is ( where M is the mass of an oxygen molecule)

0%
$\left( { V }_{ 1 }+{ V }_{ 2 } \right) /2$
0%
${ V }_{ 1 }$
0%
$\left( { V }_{ 1 }{ V }_{ 2 } \right) ^{ 1/2 }$
0%
$\sqrt { 3kT/M }$

Eleven identical rods are arranged as shown in figure. each rod has length

$l$ , cross-sectional area A and thermal conductivity of material K. ends A and F are maintained at temperatures

$T_1$ and

$T_2 (<T_1)$ , respectively. if lateral surface of each rod is thermally insulated, the rate of heat transfer

$( \frac {dQ}{dt} )$ in each rod is

0%
$( \frac {dQ}{dt})_{AB} = ( \frac {dQ}{dt})_{CD}$
0%
$( \frac {dQ}{dt})_{BE} = \frac {2}{7} \frac {(T_1-T_2) KA}{l}$
0%
$( \frac {dQ}{dt})_{CH} \neq ( \frac {dQ}{dt})_{DG}$
0%
$( \frac {dQ}{dt})_{BC} = ( \frac {dQ}{dt})_{DC}$

Two contains are filled, each with a different gas,The two containers are at the same temperature.Suppose that the molecular weight of the two gases are

$M_A and M_B$ the average moments (in magnitude) of the molecules are related as:

0%
$P_A = P_B$
0%
$P_A = \frac {M_B}{M_A} P_B$
0%
$P_ A=\left( \frac { M_ A }{ M_ B } \right)^{1/2} P_B$
0%
$P_ A=\left( \frac { M_ B }{ M_ A } \right)^{1/2} P_B$

A 2 cm thick slab of commercial thermocole

${ 100cm }^{ 2 }$ in cross -section and having thermal conductivity

$2\times { 10 }^{ -4 }$ cal

${ sec }^{ -1 }{ ^{ 0 }{ C } }^{ -1 }$ has insulating regions diferring by

$100^{ \circ }C$ . The quality of heat flowing through it in a day

0%
20.4 K cal
0%
43.2 K cal
0%
86.4 K cal
0%
23.2 K cal

A motor - car tyre has a pressure of 2 atm at 27C. It suddenly bursts. If

$\Bigg(\dfrac{C_p}{C_v} = 1.4 \Bigg)$ for air, find resulting temp :-

0%
24 K
0%
27C
0%
-27C
0%
246C

Which of the following diagrams depicts ideal gas behaviour?

A rod of length L with sides fully insulated is of a material whose thermal conductivity varies with temperature as

$K=\dfrac{\alpha}{T},$ where

$\alpha$ is a constant. The ends of the rod are kept at temperature

$T_1$ and

$T_2.$ The temperature T at x, where x is the distance from the end whose temperature is

$T_1$ is

0%
${ { T }_{ 1 }\left( \dfrac { { T }_{ 2 } }{ { T }_{ 1 } } \right) }^{ \dfrac { x }{ L } }$
0%
$\dfrac { x }{ L } ln\dfrac { { T }_{ 2 } }{ { T }_{ 1 } }$
0%
${ { T }_{ 1 }e }^{ \dfrac { { T }_{ 2 }x }{ { T }_{ 1 }L } }$
0%
${ T }_{ 1 }+\dfrac { { T }_{ 2 }-{ T }_{ 1 } }{ L } x$

The density of a liquid at

$100 ^ { \circ } \mathrm { C }$ is 8.0

$\mathrm { g } / \mathrm { cm } ^ { 3 }$ and at

$0 ^ { \circ } \mathrm { C }$ is 8.4

$\mathrm { g } / \mathrm { cm } ^ { 3 }$ , the coefficient of cubical expansion of the liquid is

0%
$10 ^ { - 4 } / ^ { \circ } \mathrm { C }$
0%
$5 \times 10 ^ { - 4 } / ^ { 0 } \mathrm { C }$
0%
$8 \times 10 ^ { - 4 } / ^ { \circ } \mathrm { C }$
0%
$4 \times 10 ^ { - 4 } / ^ { 0 } \mathrm { C }$

The thermal radiation from a hot body travels with a speed of

0%
$330m{ s }^{ -1 }$
0%
$2\times { 10 }^{ 8 }m{ s }^{ -1 }$
0%
$1200m{ s }^{ -1 }$
0%
$230m{ s }^{ -1 }$
0%
$3\times { 10 }^{ 8 }m{ s }^{ -1 }$

Explanation

Thermal radiations are infrared radiations. These are basically electromagnetic waves. All electromagnetic waves travel with a speed of

$3\times 10^8\ m/s$ .

With cold wind keeping the surface at

$20^oC$ a layer of ice on a pond grows in thickness from 20 mm to 21 mm in 10 min. Later with the surface at the same temperature it will grow from 40 mm to 42 mm in approximately

0%
10 min
0%
10.2 min
0%
20 min
0%
40 min

A refrigerator is thermally equivalent to a box of cork board 90

$\mathrm { mm }$ thick and

$\mathrm { m } ^ { 2 }$ in inner surface area, the thermal conductivity of cork being 0.05

$\mathrm { W } / \mathrm { mK }$ . The motor of the refrigerator runs 15

$\%$ of the time while the door closed. The inside wall of the door, when it is closed,is kept, on an average,

$22 ^ { \circ } \mathrm { C }$ below the temperature of the outside wall. The rate at which heat is taken from the interior wall while the motor is running is

0%
400 $\mathrm { W }$
0%
500 $\mathrm { W }$
0%
300 $\mathrm { W }$
0%
250 $\mathrm { W }$

A and B are two points on a uniform metal ring whose centre is O. The angle AOB =

$\theta$ . A angle B are maintained at two different constant temperatures. When

$\theta = 180^o$ , the rate of total heat flow from A to B is

$1.2 W$ . When

$\theta = 90^o$ then this rate will be

0%
$0.6 watt$
0%
$0.9 watt$
0%
$1.6 watt$
0%
$1.8 watt$

A body cools from

$62^{\circ}$ C to

$50^{\circ}$ C in 10 minutes and then to

$42^{\circ}$ C in next 10 minutes. The temperature of surrounding is :

0%
$23^{\circ}C$
0%
$27^{\circ}C$
0%
$26^{\circ}C$
0%
$24^{\circ}C$

Water standing in the open at

$32^0C$ evaporates because of the escape of some of the surface molecules. The heat of vaporization (

$540 cal/g$ ) is approximately equal to

$\epsilon$ n, where

$\epsilon$ is the average energy of the escaping molecules and n is the number of molecules per gram. The value of

$\epsilon$ is close to

0%
$1.62\times 10^{20}J$
0%
$14.23\times 10^{-20}J$
0%
$6.75\times 10^{-20}J$
0%
$8.31\times 10^{20}J$

CBSE Questions for Class 11 Engineering Physics Thermal Properties Of Matter Quiz 13 - MCQExams.com

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Practice Class 11 Engineering Physics Quiz Questions and Answers

CBSE Questions for Class 11 Engineering Physics Thermal Properties Of Matter Quiz 13 - MCQExams.com

0:0:1

Practice Class 11 Engineering Physics Quiz Questions and Answers

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