# Engineering Thermodynamics Questions And Answers – Set 21

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## Q1. The air standard efficiency of an Otto cycle is given by (where r = Compression ratio, and γ = Ratio of specific heats)

(A) 1 – rγ – 1
(B) 1 + rγ – 1
(C) 1 – (1/ rγ – 1)
(D) 1 + (1/ rγ – 1)

## Q2. Mond gas is obtained by

(A) Partial combustion of coal, coke, anthracite coal or charcoal in a mixed air steam blast
(B) Carbonization of bituminous coal
(C) Passing steam over incandescent coke
(D) Passing air and a large amount of steam over waste coal at about 650°C

## Q3. Relation between cp and cv is given by (where cp = Specific heat at constant pressure, cv = Specific heat at constant volume, γ = cp/cv, known as adiabatic index, and R = Gas constant)

(A) cv/ cp =R
(B) cp – cv = R
(C) cv = R/ γ-1
(D) Both (B) and (C)

## Q4. According to Regnault’s law, the specific heat at constant pressure (cp) and specific heat at constant volume (cv) _ with the change in pressure and temperature of the gas.

(A) Change
(B) Do not change
(C) Both (A) and (B)
(D) None of these

## Q5. The mass of carbon per kg of flue gas is given by

(A) (11/3) CO2 + (3/7) CO
(B) (3/7) CO2 + (11/3) CO
(C) (7/3) CO2 + (3/11) CO
(D) (3/11) CO2 + (7/3) CO

## Q6. Petrol is distilled at

(A) 65° to 220°C
(B) 220° to 345°C
(C) 345° to 470°C
(D) 470° to 550°C

(A) Oxygen
(B) Nitrogen
(C) Hydrogen
(D) Methane

## Q8. A cycle consisting of two constant pressure and two isentropic processes is known as

(A) Carnot cycle
(B) Stirling cycle
(C) Otto cycle
(D) None of these

## Q9. Which of the following is correct?

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

(A) Oxygen
(B) Sulphur
(C) Nitrogen
(D) Carbon

## Q11. One kg of carbon monoxide requires 4/7 kg of oxygen and produces

(A) 11/3 kg of carbon dioxide gas
(B) 7/3 kg of carbon monoxide gas
(C) 11/7 kg of carbon dioxide gas
(D) 8/3 kg of carbon monoxide gas

## Q12. The efficiency of Diesel cycle increases with

(A) Decrease in cut-off
(B) Increase in cut-off
(C) Constant cut-off
(D) None of these

(A) 12
(B) 14
(C) 16
(D) 32

## Q14. The general gas energy equation is (where Q1 – 2 = Heat supplied, dU = Change in internal energy, and W1 – 2 = Work done in heat units)

(A) Q1 – 2 = dU + W1 – 2
(B) Q1 – 2 = dU – W1 – 2
(C) Q1 – 2 = dU/W1 – 2
(D) Q1 – 2 = dU × W1 – 2

## Q15. A tri-atomic molecule consists of __ atoms.

(A) One
(B) Two
(C) Three
(D) Four

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