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# Thermodynamics Practice Level - 1

## 30 Questions MCQ Test | Thermodynamics Practice Level - 1

Description
This mock test of Thermodynamics Practice Level - 1 for Class 11 helps you for every Class 11 entrance exam. This contains 30 Multiple Choice Questions for Class 11 Thermodynamics Practice Level - 1 (mcq) to study with solutions a complete question bank. The solved questions answers in this Thermodynamics Practice Level - 1 quiz give you a good mix of easy questions and tough questions. Class 11 students definitely take this Thermodynamics Practice Level - 1 exercise for a better result in the exam. You can find other Thermodynamics Practice Level - 1 extra questions, long questions & short questions for Class 11 on EduRev as well by searching above.
QUESTION: 1

### A piston-cylinder device initially contains air at 150 kPa and 27°C. At this state, the volume is 400 litre. The mass of the piston is such that a 350 kPa pressure is required to move it. The air is now heated until its volume has doubled. Determine the total heat transferred to the air.

Solution:

Qin – Wout = ΔU = m(u3 –u1)
m = P1V1/RT1 = 0.697 kg
u1 = u@ 300 K = 214.36 kJ/kg
u3 = u@ 1400 K = 1113.43 kJ/kg
Therefore Qin = 767 kJ.

QUESTION: 2

Solution:
QUESTION: 3

### A cylindrical metal rod of length L0 is shaped into aring with a small gap as shown. On heating the system Solution:
QUESTION: 4

Two holes of unequal diameters d1 and d2 (d1 > d2) are cut in a metal sheet. If the sheet is heated Solution:
QUESTION: 5

Work done in converting 1 g of ice at - 100C intostream at 1000 C is

Solution:
QUESTION: 6

Compared to a burn due to water at 1000C, a burndue to stream at 1000C is

Solution:
QUESTION: 7

Three liquids with masses m1, m2, m3 are throughly mixed. If their specific heats are c1, c2, c3 and their temperatures T1, T2, T3, respectively, then the temperature of the mixture is

Solution:
QUESTION: 8

Two rods (one semi-circular and other straight) ofsame material and of same cross-sectional area arejoined as shown in Fig. The points A and B aremaintained at different temperatures. The ratio of theheat transferred through a cross section of a semicircularrod to the heat transferred through a crosssection of the straight rod in a given time is Solution: QUESTION: 9

A point source of heat of power P is placed at thecentre of a spherical shell of mean radius R. Thematerial of the shell has thermal conductivity K. Ifthe temperature difference between the outer andthe inner surface of the shell is not to exceed T, thenthe thickness of the shell should not be less than

Solution:
QUESTION: 10

Three rods of same dimensions are arranged as shownin Fig. They have thermal conductivities K1, K2 and K3.The points P and Q are maintained at different temperatures for the heat of flow at the same rate along PRQ and PQ. Which of the following options is correct? Solution:
QUESTION: 11

The coefficient of thermal conductivity of copper isnine times that of steel. In the composite cylindricalbar shown in Fig., what will be the temperature atthe junction of copper and steel? Solution:
QUESTION: 12

Six identical conducting rods are joined as shown inFig. Points A and D are maintained at temperatures 2000C and 200C, respectively. The temperature of junction B will be Solution:
QUESTION: 13

Figure shown two air-filled bulbs connected by a U-tube partly filled with alcohol. What happens to the levels of alcohol in the limbs X and Y when an electric bulb placed midway between the bulbs is lighted? Solution:
QUESTION: 14

The rectangular surface of area 8 cm × 4 cm of ablack body at a temperature of 1270C emits energy at the rate of E per second. If the length and breadth of the surface are each reduced to half of the initial value and the temperature is raised to 3270C, the rate of emission of energy will become

Solution:
QUESTION: 15

The rates of cooling of two different liquids put inexactly similar calorimeters and kept in identicalsurroundings are the same if

Solution:
QUESTION: 16

Hot water cools from 600C to 500C in the first 10 min and to 420C in the next 10 min. The temperature of the surrounding is

Solution:
QUESTION: 17

There are two thin spheres A and B of the samematerial and same thickness. They behave like black bodies. Radius of A is double that of B and both have same temperature T. When A and B are kept in a room of temperature T0 (< T), the ratio of their rates of cooling is (assume negligible heat exchange between A and B)

Solution:
QUESTION: 18

Heat is required to change 1 kg of ice at - 200C intostream. Q1 is the heat needed to warm the ice from -200C to 00C, Q2 is the heat needed to melt the ice, Q3is the heat needed to warm the water from 00C to1000C and Q4 is the heat needed to vapourize the water. Then

Solution:
QUESTION: 19

A piece of metal floats in mercury. The coeficients of volume expansion of the metal and mercury are γ1 and γ2 , respectively. If the temperatures of both mercury and the metal are increased by ΔT , the fraction of the volume of the metal submerged inmercury changes by the factor of

Solution:
QUESTION: 20

Three rods of identical cross-sectional area and madefrom the same metal form the sides of an isoscelestriangle ABC right angled at B. The points A and Bare maintained at temperatures T and ,respectively, in the steady state. Assuming that only heat conduction takes place, temperature of point C is Solution:
QUESTION: 21

When the temperature of a black body increases, itis observed that the wavelength corresponding to maximum energy changes from 0.26 μm to 0.13 μm.The ratio of the emissive powers of the body at therespective temperatures is

Solution:
QUESTION: 22

A box contains N molecules of a perfect gas attemperature T1 and pressure P1. The number ofmolecules in the box is doubled keeping the totalkinetic energy of the gas same as before. If the newpressure is P2 and temperature T2, then

Solution:
QUESTION: 23

The expansion of units mass of a perfect gas atconstant pressure is shown in Fig. Here. Solution:
QUESTION: 24

A gas is filled in the cylinder shown in Fig. The twopistons are joined by a string. If the gas is heated,the right piston will Solution:
QUESTION: 25

If pressure of a gas contained in a closed vessel inincreased by 0.4% when heated by 10C, the initial temperature must be

Solution:
QUESTION: 26

Pressure versus temperature graph of an ideal gasof equal number of moles of different volumes isplotted as shown in Fig. Choose the correctalternative. Solution:
QUESTION: 27

​A gas is heated at a constant pressure. The fraction of heat supplied used for external work is

Solution:
QUESTION: 28

A monatomic gas expands at constant pressure onheating. The percentage of heat supplied thatincrease the internal energy of the gas and that isinvolved in the expansion is

Solution:
QUESTION: 29

The average degrees of freedom per molecule for a gas are 6. The gas performs 25 J of work when it expands at constant pressure. The heat absorbed y gas is

Solution:
QUESTION: 30

A and B are two isolated spheres kept in closeproximity so that they can exchange energy byradiation. The two spheres have identical physicaldimensions but the surface of A behave like aperfectly black body while the surface of B reflects 20% of all the radiations it receives. They are isolatedfrom all other sources of radiation. Solution: