**1. An insulated rigid vessel contains a mixture of fuel and air. The mixture is ignited by a minute spark. The contents of vessel experience**

(a) increase in temperature, pressure and energy

(b) decrease in temperature, pressure and energy

(c) increase in temperature and pressure but increase in energy

(d) Increase in temperature and pressure but no change in energy

Answer

Option (d) is correct

**It is obvious that energy cannot be created its just transferred from one form to another.**

** 2. The specific heat of ideal gas depend on **

(a) Temperature

(b) Volume

(c) Molecular weight and structure

(d) Pressure

** 3. Thermal power plant works on**

(a) Carnot cycle

(b) Joule cycle

(c) Rankine cycle

(d) Brayton cycle

**4. In an isothermal process, the internal energy of molecules**

(a) Increases

(b) Decreases

(c) Depends on temperature

(d) Remains constant

Answer

Option (d) is correct

**Internal energy is a function of temperature only.**

** 5. For reversible adiabatic process, change in entropy is**

(a) positive

(b) negative

(c) zero

(d) depends on pressure

** 6. A cylinder contains 5 m**^{3} of an ideal gas at a pressure of 1. This gas is compressed in a reversible isothermal process till its pressure increases to 5 bar. The work in kJ required for this process is

(a) 804.7

(b) 953.5

(c) 987.5

(d) 1012.3

Answer

Option (a) is correct

**Note: Typing error by ISRO since pressure 5 bar is given so we assume 1 is also in bar.**

**For isothermal process, we have**

\(P_1v_1=P_2v_2;\;\; 1\times5=5\times v_2;\;\;v_2=1\;m^3\)

**Work is given by**

\(\large W=P_1v_1\ln\frac{v_2}{v_1}\)

\(\large W=5\times100\ln\frac{1}{5}\;kJ=-804.71\;kJ\)

** 7. A steel ball of mass 1 kg and specific heat 0.4 kJ/kg is at a temperature of 60 deg C. It is dropped into 1 kg of water at 20 deg C. The final steady temperature of water is **

(a) 23.48 deg C

(b) 32.28 deg C

(c) 20 deg C

(d) 30 deg C

Answer

Option (a) is correct

**Using energy balance, we have**

\(1\times0.4\times(60-T)=1\times4.18\times(T-20)\)

\(T\approx 23.48\;deg\;C\)

**8. A Bell-Coleman cycle is a reversed **

(a) Carnot cycle

(b) Otto cycle

(c) Joule cycle

(d) Rankine cycle

**9. A free bar of length l is uniformly heated from 0°C to a temperature t°C. α is the coefficient of linear expansion and E is the modulus of elasticity. The stress in the bar is **

(a) α TE

(b) E/ α T

(c) Zero

(d) None of the above

Answer

Option (c) is correct

**Since the bar is free to expand there are no stresses induced in the bar.**

**10. The materials having same elastic properties in all directions are called**

(a) elastic materials

(b) uniform materials

(c) isotropic materials

(d) plastic materials

Answer

Option (c) is correct

**Isotropic material has same property in all direction at a point. Homogneous material has same property in one direction at any point.**

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