Engineering Thermodynamics MCQs

Question 1

The ideal efficiency of a Brayton cycle without regeneration, with increase in pressure ratio will

Accepted Answer

Increase

Answer

Decrease

Answer

Remain unchanged

Answer

Increase/decrease depending on application

Question 2

The ideal efficiency of a Brayton cycle with regeneration, with increase in pressure ratio will

Accepted Answer

Decrease

Answer

Increase

Answer

Remain unchanged

Answer

Increase/decrease depending on application

Question 3

Absolute zero pressure will occur

Accepted Answer

When molecular momentum of the system becomes zero

Answer

At sea level

Answer

Under vacuum conditions

Answer

At a temperature of 273°K

Question 4

In a free expansion process

Accepted Answer

Both (A) and (B) above

Answer

Work done is zero

Answer

Heat transfer is zero

Answer

Work done is zero but heat increases

Question 5

The ratio of two specific heats of air is equal to

Accepted Answer

1.41

Answer

0.17

Answer

0.24

Answer

0.1

Question 6

One kg of carbon produces ________ kg of carbon dioxide.

Accepted Answer

$$\frac{{11}}{3}$$

Answer

$$\frac{3}{7}$$

Answer

$$\frac{{11}}{7}$$

Answer

$$\frac{4}{{11}}$$

Question 7

One kg of carbon produces __________ kg of carbon dioxide.

Accepted Answer

$$\frac{{11}}{3}$$

Answer

$$\frac{3}{7}$$

Answer

$$\frac{7}{3}$$

Answer

$$\frac{3}{{11}}$$

Question 8

If a certain amount of dry ice is mixed with same amount of water at 80°C, the final temperature of mixture will be

Accepted Answer

0°C

Answer

80°C

Answer

40°C

Answer

20°C

Question 9

The air standard efficiency of an Otto cycle is given by (where r = Compression ratio and $$\gamma $$ = Ratio of specific heats)

Accepted Answer

$$1 - \frac{1}{{{{	ext{r}}^{\gamma - 1}}}}$$

Answer

$$1 - {{	ext{r}}^{\gamma - 1}}$$

Answer

$$1 + {{	ext{r}}^{\gamma - 1}}$$

Answer

$$1 + \frac{1}{{{{	ext{r}}^{\gamma - 1}}}}$$