# Mechanical Engineering Thermodynamics – Set 09

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## Q1. Universal gas constant is defined as equal to product of the molecular weight of the gas and

(A) Specific heat at constant pressure
(B) Specific heat at constant volume
(C) Ratio of two specific heats
(D) Gas constant

## Q2. Compressed air coming out from a punctured football

(A) Becomes hotter
(B) Becomes cooler
(C) Remains at the same temperature
(D) May become hotter or cooler depending upon the humidity of the surrounding air

(A) 3 to 6
(B) 5 to 8
(C) 10 to 20
(D) 15 to 30

## Q4. Which of the following is correct?

(A) Gauge pressure = Absolute pressure + Atmospheric pressure
(B) Absolute pressure = Gauge pressure + Atmospheric pressure
(C) Absolute pressure = Gauge pressure – Atmospheric pressure
(D) Atmospheric pressure = Absolute pressure + Gauge pressure

Answer: (B) Absolute pressure = Gauge pressure + Atmospheric pressure

(A) Meter
(B) Centimeter
(C) Kilometer
(D) Millimeter

## Q6. Coke is produced

(A) When coal is strongly heated continuously for 42 to 48 hours in the absence of air in a closed vessel
(B) From the finely ground coal by moulding under pressure with or without a binding material
(C) When coal is first dried and then crushed to a fine powder by pulverizing machine
(D) By heating wood with a limited supply of air to a temperature not less than 280°C

Answer: (A) When coal is strongly heated continuously for 42 to 48 hours in the absence of air in a closed vessel

## Q7. The heat and mechanical energies are mutually convertible. This statement was established by

(A) Boyle
(B) Charles
(C) Joule
(D) None of these

## Q8. Which is the incorrect statement about Carnot cycle?

(A) All the heat engines are based on Carnot cycle
(B) It is used as the alternate standard of comparison of all heat engines
(C) It provides concept of maximising work output between the two temperature limits
(D) All of the above

Answer: (A) All the heat engines are based on Carnot cycle

## Q9. A process, in which the temperature of the working substance remains constant during its expansion or compression, is called

(B) Isothermal process
(C) Hyperbolic process
(D) Polytropic process

## Q10. An isothermal process is governed by

(A) Gay-Lussac law
(B) Charles’ law
(C) Boyle’s law

## Q11. Which of the following gas is mostly used in town for street and domestic lighting and heating?

(A) Mond gas
(B) Coal gas
(C) Producer gas
(D) Coke oven gas

## Q12. According to first law of thermodynamics

(A) Mass and energy are mutually convertible
(B) Carnot engine is most efficient
(C) Heat and work are mutually convertible
(D) Mass and light are mutually convertible

Answer: (C) Heat and work are mutually convertible

## Q13. An adiabatic wall is one which

(A) Prevents thermal interaction
(B) Permits thermal interaction
(C) Encourages thermal interaction
(D) Discourages thermal interaction

## Q14. The first law of thermodynamics is the law of

(A) Conservation of mass
(B) Conservation of energy
(C) Conservation of momentum
(D) Conservation of heat

## Q15. The same volume of all gases would represent their

(A) Densities
(B) Specific weights
(C) Molecular weights
(D) Gas characteristic constants

## Q16. A cycle consisting of one constant pressure, one constant volume and two isentropic processes is known as

(A) Otto cycle
(B) Stirling cycle
(C) Carnot cycle
(D) Diesel cycle

## Q17. Water contained in a beaker can be made to boil by passing steam through it

(A) At atmospheric pressure
(B) At a pressure greater than atmospheric pressure
(C) Any pressure
(D) Not possible

Answer: (B) At a pressure greater than atmospheric pressure

## Q18. The efficiency of Carnot cycle is maximum for

(A) Gas engine
(B) Petrol engine
(C) Steam engine
(D) Reversible engine

(A) Very low
(B) Low
(C) High
(D) Very high