1. The commonly used gaseous coolants in refrigeration are:

(a) Ammonia, Sulphur dioxide, Carbon dioxide and Hydrogen
(b) Nitrogen, Nitrogen dioxide, Carbon dioxide and Freon
(c) Ammonia, Sulphur dioxide, Carbon dioxide and Freon
(d) Nitrogen, Sulphur dioxide, Nitrogen dioxide and Hydrogen

Answer: (c)

2. An e.m.f. in a thermocouple with the test junction at 𝑡 °𝐶𝐶 on gas thermometer scale and reference junction at ice point is:
The millivoltmeter is calibrated at ice and steam points. When the gas thermometer reads 50°𝐶, the thermocouple will read:
(a) 60.66°𝐶
(b) 58.33°𝐶
(c) 56.66°𝐶
(d) 54.33°𝐶

Answer: (b)

3. 

Answer: (b)

4. ′Nitrogenous oxygen demand′ (NBOD) is oxygen needed to:
(a) Convert ammonia to nitrate
(b) Convert nitrogen dioxide to nitrogen trioxide
(c) Denitrifying bacteria to grow
(d) Oxidize organic matters

Answer: (a)

5. A sample of groundwater has . Its total hardness will be nearly:
(a) 2.4 meq/L
(b) 3.8 meq/L
(c) 4.4 meq/L
(d) 5.8 meq/L

Answer: (d)

6. Trickling filter is used in:
(a) Filtering fruit juice
(b) Secondary / biological treatment of wastewater
(c) Primary treatment of wastewater
(d) Tertiary treatment of wastewater

Answer: (b)

7. 

Answer: (c)


8. 

(a) Coal gas
(b) Oil gas
(c) Natural gas
(d) Producer gas

Answer: (c)

9. Which of the following are the properties of CNG?
1. It ignites at a higher temperature
2. The conversion is very easy
3. The operating cost is much lower
4. Combustion of this gas leads to more 𝐶𝐶𝐶 emission
5. Emission contain no unregulated pollutants

(a) 1, 2, 3 and 4 only
(b) 1, 3, 4 and 5 only
(c) 1, 2, 3 and 5 only
(d) 2, 3, 4 and 5 only

Answer: (c)

10. Consider the following steps for manufacturing of coal gas:
1. The gas is scrubbed by passing through a hydraulic main
2. Coal is carbonized in absence of air about 1300°𝐶
3. Tar and ammonia, present in the gas are removed by scrubbing with water in a scrubber
4. Tar is removed by cooling the gas in a huge water cooled heat exchanger called condenser
5. The gas is freed from hydrogen sulphide by passing it over moist ferric oxide, contained in a purifier
6. The cooled gas is then scrubbed with creosote oil which dissolves benzol and naphthalene

What is the correct sequence of steps occurred?
(a) 2, 1, 4, 3, 6 and 5
(b) 1, 2, 4, 3, 5 and 6
(c) 1, 2, 3, 4, 5 and 6
(d) 2, 3, 1, 3, 6 and 5

Answer: (a)