Chemistry of Gases and Applications

In the liver's urea cycle (ornithine cycle), toxic ammonia (NH₃) combines with carbon dioxide (CO₂) to form urea, which is then excreted by kidneys. This is the primary pathway for nitrogen waste removal in humans. HCl is stomach acid, chromium is a mineral, and ammonium dioxide is not a biological product.

Nitrous oxide (N2O), commonly known as laughing gas, is the correct answer. It's a colorless, non-flammable gas with a slightly sweet odor that can induce laughter and euphoria when inhaled. Nitrogen dioxide is a toxic brown gas, carbon oxide is not a standard chemical name (carbon monoxide or carbon dioxide are), and ammonium oxide is not a stable compound.

Ozone (O3) in the stratosphere absorbs UV radiation and traps heat in the atmosphere, making it a greenhouse gas. While CO2 is the most abundant greenhouse gas, the question specifically asks for 'a' heat-trapping gas, and O3 is correct.

Nitroglycerine is a powerful explosive used in dynamite and mining. The other options are not explosives - Phosphorus Trichloride (chemical reagent), Mercuric oxide (inorganic compound), and Graphite (form of carbon used in pencils and electrodes).

Ammonia (NH3) is widely used as a fertilizer because it contains nitrogen, an essential nutrient for plant growth. NH3 can be directly applied to soil or used to produce other nitrogen fertilizers like urea. The other options (CO, O3, CO2) are not used as fertilizers - CO is toxic, O3 is an air pollutant at ground level, and CO2 is not a direct fertilizer though plants need carbon.

Tear gas contains chlorine-based compounds like CS gas (chlorobenzalmalononitrile) or CN gas (chloroacetophenone). The 'chlorine' in these compounds is what gives tear gas its irritating properties, causing tears and respiratory discomfort. Hydrogen, nitrogen dioxide (NO2), and sulfur are not the primary components of standard tear gas formulations.

Oxygen (O) is NOT a noble gas - it is a highly reactive nonmetal in Group 16. The noble gases are Helium, Neon, Argon, Krypton, Xenon, and Radon in Group 18.

TNT (trinitrotoluene) is a well-known explosive compound used in military and industrial applications. Nitroglycerin is also a highly explosive liquid used in dynamite. Both 'b and c' are correct explosives.

The Bhopal gas tragedy of December 2-3, 1984 was caused by the accidental release of methyl isocyanate (MIC) gas from a Union Carbide pesticide plant. This toxic gas exposure killed thousands immediately and continues to affect survivors decades later.

The Agnya chakra (third eye chakra) is traditionally not associated with any of the four classical elements (earth, water, fire, air). It represents light, consciousness, and transcendence beyond the physical elements. The lower six chakras correspond to earth, water, fire, air, space, and mind, while Agnya represents a higher state of awareness.

Methyl isocyanate (MIC) was the toxic gas that leaked from the Bhopal plant storage tank. It is a highly volatile and toxic chemical intermediate used in pesticide production.

Du Pont trademarked their hydro-chloro-fluorocarbon compounds as Freon. Freon became the generic term for CFC refrigerants used in air conditioning and refrigeration before being phased out due to ozone layer concerns. CFC is the chemical class name, not Du Pont's brand.

The correct answer is A (Hydrogen). Weather balloons have traditionally used hydrogen gas because it is lighter than air and provides good lift. While helium is also used (especially for safety), hydrogen has been more common for weather balloons due to its lower cost and greater buoyancy. Oxygen and carbon dioxide are heavier than air and cannot lift balloons.

The Big Bang produced primarily hydrogen and helium, the two lightest elements. These formed from the cooling of the initial hot, dense state of the universe. Heavier elements were later produced in stars.

Nitrogen makes up approximately 78% to 79% of the Earth's atmosphere by volume. The value 0.79 represents the fractional equivalent (79%). Oxygen accounts for about 21%, with other gases making up the remainder.