Heat and Thermodynamics

Thermodynamic processes are indicated in the following diagram

Match the following :

Column - I Column - II

P Process I a Adiabatic

Q Process II b Isobaric

R Process III c Isochoric

S. Process IV d Isothermal

• P → a, Q → c, R → d, S → b

• P → c, Q → d, R → b, S → a

• P → c, Q → d, R → b, S → a

• P → d, Q → b, R → a, S → c

A gas mixture consists of 2 moles of O₂ and 4 moles of Ar at temperature T. Neglecting all vibrational modes, the internal energy system is

• 4RT

• 15RT

• 9RT

• 11RT

A Carnot engine having an efficiency of 1 /10 as heat engine, is used as a refrigerator. If the work done on the system is 10 J, the amount of energy absorbed from the reservoir at lower temperature is

• 1 J

• 90 J

• 99 J

• 100 J

A black body is at a temperature of 5760 K. The energy of radiation emitted by the body at wavelength 250 nm is U₁, at wavelength 500 nm is U₂ and that at 1000 nm is U_3. Wien's constant, b = 2.88 × 10⁶ nmK. Which of the following is correct ?

• U₃ = 0

• U₁ > U₂

• U₂ > U₁

• U₁ = 0

A gas is compressed isothermally to half its initially volume. The same gas is compressed separately through an adiabatic process until its volume is again reduced to half. Then

• compressing the gas through adiabatic process will require more work to be done

• compressing the gas isothermally or adiabatically will require the same amount of work

• which of the case (whether compression through isothermal or through adiabatic process) requires more work will depend upon the atomicity of the gas

• compressing the gas isothermally will require more work to be done

A piece of ice falls from a height h so that it melts completely.Only one - quarter of the heat produced is absorbed by the ice and all energy of ice gets converted into heat during its fall. The value of h is [Latent heat of ice is 3.4 × 10⁵ J/kg and g = 10 N/kg]

• 544 km

• 136 km

• 68 km

• 34 km

A refrigerator works between 4°C and 30°C it is required to remove 600 calories of heat every second on order to keep the temperature of the refrigerated space constant. The power required is

(Take,1 cal - 4.2 Joules)

• 23.64 W

• 236.5 W

• 2365 W

• 2.365 W

Two identical bodies are made of a material for which the heat capacity increases with temperature. One of these is at 100°C,while the other one is at 0°C.If the two bodies are brought into contact, then assuming no heat loss, the final common temperature is

• 50°C

• more than 50°C

• less than 50°C but greater than 0°C

• 0°C

A body cools from a temperature 3T to 2T in 10 minutes. The room temperature is T. Assume that Newton's law of cooling is applicable. The temperature of the body at the end of next 10 minutes will be

• 7/4 × T

• 3/2 × T

• 4/3 × T

• T

One mole of an ideal monatomic gas undergoes a process described by the equation pV3 = constant. The heat capacity of the gas during this process is

• 3/2 × R

• 5/2 × R

• 2R

• R