Chemistry of Gases and Applications

Nitrous oxide (N2O) is commonly called laughing gas because it inhalation produces euphoria and laughter. It was discovered by Joseph Priestley and has been used as an anesthetic and analgesic in dentistry and surgery for over 150 years.

Tetraethyl lead (TEL) was historically added to petrol as an anti-knocking agent to improve engine performance by preventing premature fuel combustion. It works by increasing the octane rating of gasoline, allowing for smoother engine operation. The other options are incorrect because TEL is not used as a mosquito repellent, pain killer, or fire extinguisher.

Carbon dioxide is the primary gas used in fire extinguishers because it displaces oxygen and does not support combustion, effectively smothering fires. It's particularly useful for electrical fires as it's non-conductive. Carbon monoxide is toxic and would be dangerous, while neon and nitrogen are not effective fire suppressants in standard applications.

Carbon dioxide (CO2) is produced during fermentation when yeast converts sugars into alcohol and gas. The CO2 bubbles create the airy, risen texture in bread. This process is called leavening and is essential for making bread light and porous.

Gases liquefy most easily under conditions that bring molecules closer together and reduce their kinetic energy. Low temperature reduces molecular motion, while high pressure compresses the gas, both favoring the liquid state according to Le Chatelier's principle.

Sublimation is the phase transition from solid directly to gas (or vice versa) without passing through the liquid phase. Only the physical state changes - the chemical identity remains unchanged. Oxidation, reduction, and decomposition are all chemical changes.

The reaction of water with calcium carbide produces acetylene gas and calcium hydroxide. This is a standard laboratory preparation method for acetylene.

Carbon tetrachloride decomposes at high temperatures to form phosgene gas (COCl2), which is highly toxic. The question asks what gas is produced, and since phosgene is not listed as an option, the correct choice is 'None of these' - meaning the actual gas (phosgene) is not among the given choices.

It is heavier than air.

At the same temperature and pressure, all the gases will have the same kinetic energy.

Neon has lower density than air.

The government is planning to impose a strict regulatory regime to check the easy availability of ammonium nitrate, which is a preferred ingredient in improvised explosive devices (lEDs) used in terror strikes. The Draft Ammonium Nitrate Rules, 2009, prepared by the Ministry of Home Affairs (MHA), seeks to regulate and put restrictions on the loading and unloading of bulk ammonium nitrate from a ship, its import, export, transport, possession for sale and use, except as permitted under the rules. The use of ammonium nitrate, also commonly used as fertiliser, has been reported in bomb explosions in Varanasi, Lucknow, Jaipur, Faizabad, Hyderabad and the serial blasts in Bangalore.

2

Potassium sulphide is an inorganic compound with the formula K₂S. Potassium sulphides are formed when black powder is burned and are important intermediates in many pyrotechnic effects, such as senko hanabi and some glitter formulations.

When water is poured on calcium carbide (CaC2), acetylene gas (C2H2) is produced through a chemical reaction. The reaction is: CaC2 + 2H2O → Ca(OH)2 + C2H2. Acetylene is used in welding torches and was historically used for lighting. Pentane, methane, and ethane are different hydrocarbons not produced by this reaction.