Chemistry of Gases and Applications

Ammonia (NH3) is widely used in refrigeration systems due to its excellent thermodynamic properties, high heat transfer efficiency, and zero ozone depletion potential. It's commonly used in industrial refrigeration and cold storage.

LPG (Liquefied Petroleum Gas) is naturally odorless, so sulfur-containing compounds like ethyl mercaptan (ethanethiol) or thiophane are added as odorants to make leaks detectable. These compounds have an extremely strong smell detectable at very low concentrations (as low as 1 part per billion). The sulfur in these compounds produces the characteristic 'rotten egg' smell.

CFCs (Chlorofluorocarbons) were widely used as refrigerants in refrigerators and air conditioning systems, and as propellants in aerosol sprays. However, they were never used in fire extinguishers - fire extinguishers typically use carbon dioxide, foam, dry chemical powders, or halon (before its phase-out). CFCs were phased out globally under the Montreal Protocol due to their ozone-depleting properties.

Acetylene gas (C2H2) is commonly used for artificial ripening of fruits, especially in developing countries. It acts similarly to ethylene (the natural ripening hormone in fruits). While ethylene is the preferred industrial ripening agent worldwide, acetylene is cheaper and more accessible. The other gases listed (ethane, hydrogen, CO2) do not stimulate fruit ripening.

Mustard gas (sulfur mustard) was extensively used as a chemical weapon during World War I, causing severe blistering of the skin, eyes, and respiratory tract. It was called mustard gas due to its mustard-like odor and yellow-brown color. While hydrogen cyanide was also used, mustard gas was one of the most widely deployed chemical agents. Carbon monoxide and water gas were not used as chemical weapons.

Chlorine is widely used for water purification because it effectively kills bacteria, viruses, and other microorganisms. It acts as a strong disinfectant that prevents waterborne diseases and provides residual protection in distribution systems. Oxygen, ammonia, and carbon dioxide do not have disinfectant properties suitable for water treatment.

Gobar gas (biogas) primarily contains methane (50-70%) produced by anaerobic digestion of animal dung. Methane is the combustible component that makes biogas useful as fuel. Carbon dioxide is present as a byproduct but is not the main combustible component. Ethane and hydrogen are not significant components of biogas.

Fire extinguishers commonly release carbon dioxide, which smothers fires by displacing oxygen and also has a cooling effect. CO2 extinguishers are particularly useful for electrical and flammable liquid fires. Hydrogen is flammable, nitrogen is used in some specialized systems, and carbon monoxide is toxic.

Liquefied Petroleum Gas (LPG) used for cooking is primarily a mixture of propane and butane. These hydrocarbons can be easily liquefied under moderate pressure for storage and transport, making them ideal for household cooking applications.

LPG (Liquefied Petroleum Gas) used for cooking is primarily a mixture of butane and propane. These hydrocarbons can be easily liquefied under pressure for storage and transport.

Acetylene gas (C2H2) is commonly used for artificial ripening of fruits in commercial settings. It mimics the natural ethylene produced by fruits during ripening. While ethylene is the natural ripening hormone, acetylene breaks down to produce ethylene and is cheaper and more readily available.

Only option (2) has the correct phrasing.

Ans : 1.

Ans : 2.

Ethyl mercaptan (the spelling used is 'mercaptate' here) is added to LPG because it has a very strong, unpleasant odor that makes leaks immediately detectable. Pure LPG is odorless, so this odorant is a critical safety measure. The other options are not used for this purpose.