91. According to British Gas Engineers Handbook, the maximum allowed gas concentration of CO2, CO and H2S in the environment are:

(a) 5000 ppm ,200 ppm and 40 ppm
(b) 3000 ppm ,200 ppm and 20 ppm
(c) 5000 ppm ,100 ppm and 20 ppm
(d) 3000 ppm ,100 ppm and 40 ppm

Answer: (c)

92. In coal mining production of CH4 gas by in-situ gasification, the reactions take place in three reaction zones, are:
(a) Oxidation, reduction and hydrolysis
(b) Oxidation, reduction and pyrolysis
(c) Reduction, hydration and pyrolysis
(d) Reduction, hydration and hydrolysis

Answer: (b)

93. Coal, in its natural state in the seam is usually a material with low permeability and it is formed in layers under:
(a) Low pressure and only by supplying oxygen at high pressure
(b) Great pressure only
(c) Low pressure and only by supplying oxygen at low pressure
(d) Great pressure and only by supplying oxygen at low pressure

Answer: (b)

94. Which one of the following coals is hard in nature, have little porosity, low reactivity as well as low volatile matter content with fixed carbon present in the coal ranges as high as 92% - 98%, semi metallic, ignite with difficulty and burns with short flame without smoke?
(a) Anthracite coal
(b) Semi bituminous coal
(c) Bituminous coal
(d) Lignite or brown coal

Answer: (a)

95. Depolyerization of coal is accomplished by:
(a) Oxidation, reduction and hydrogenation of reactive solvents
(b) Hydrogenation, oxidation, reduction and reactive solvents
(c) Oxidation, reduction and reactive solvents
(d) Hydrogenation, pyrolysis, oxidation and reactive solvents

Answer: (d)

96. The two steps acid treatments for the demineralization of coal are:
(a) Aqua-regia to remove all metal salts and then is followed by a HCl treatment
(b) NHO3 to remove all metal salts and then is followed by a HF treatment
(c) H2SO4 to remove all metal salts and then is followed by a HCl treatment
(d) HCl to remove all metal salts and then is followed by a HF treatment

Answer: (d)

97. Equilibrium moisture in coal is defined as, an amount of moisture contained in coal at:
(a) 30°𝐶 in a relative humidity of 96%-97%
(b) 38°𝐶 in a relative humidity of 86%-87%
(c) 46°𝐶 in a relative humidity of 76%-77%
(d) 52°𝐶 in a relative humidity of 66%-67%

Answer: (a)

98. In acetylene production from coal by plasma process, the efficiency of the process depends upon:
(a) Physical nature, non-volatile matter content and oxygen percentage in the coal
(b) Particle size, volatile matter content and oxygen percentage in the coal
(c) Physical nature, volatile matter content and carbon dioxide percentage in the coal
(d) Particle size, volatile matter content and carbon dioxide percentage in the coal

Answer: (b)

99. Which of the following procedures must not be conducted in platinum apparatus during quantitative chemical analysis?
1. Fusion with sodium carbonate or fusion mixture
2. Evaporation with hydrochloric acid
3. Heating with Aqua regia
4. Heating with liquid mixtures which evolve bromine or iodine

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

Answer: (c)

100. 

Answer: (a)