Chemistry of Gases and Applications

It is a measure of the amount of gas which a surface contains; more specifically, it is the product of the pressure and time of exposure (normal unit is the Langmuir, where 1 L = 10-6 Torr s).

Adsorption of gases on solids depends on all the above factors.

Carbon Monoxide (CO) is highly toxic because it binds to hemoglobin in red blood cells much more strongly than oxygen does. This prevents oxygen from being transported through the body, leading to suffocation. It is definitely not friendly and is a dangerous silent killer.

Carbon dioxide

(the colourless gas nitrogen is also present). Option (1) provides the correct word order. Options (2) ,(3) and (4) make use of unnecessary words, which make the sentence incomplete and meaningless. 

It is correct as sulphur dioxide has a pungent smell.

Dry ice is the solid form of carbon dioxide (CO2). It sublimates (turns directly from solid to gas) at -78.5°C at normal atmospheric pressure, which is why it's called 'dry' - it doesn't melt into a liquid first. Options A and B are incorrect because dry ice is neither ammonia nor sulfur dioxide. Option C is misleading because all carbon dioxide in solid form is 'dry' ice.

Ethylene is a natural plant hormone that triggers and regulates the fruit ripening process. It acts as a chemical signal that stimulates the production of enzymes which break down cell walls and convert starches to sugars, making fruits softer and sweeter. Commercially, fruits are exposed to ethylene gas to accelerate and control ripening.

While hydrogen is indeed the lightest gas, this is not the complete scientific explanation for its absence in the atmosphere. Being so light, hydrogen atoms can escape Earth's gravitational pull and don't remain concentrated in the lower atmosphere. Additionally, hydrogen is highly reactive and quickly forms compounds (like water with oxygen), so free molecular hydrogen doesn't accumulate. Option B captures the primary reason related to its low density, though the full explanation involves both escape velocity and chemical reactivity.

Acetylene (C2H2) is used in artificial fruit ripening, typically produced by reacting calcium carbide with water. It mimics the natural ripening hormone ethylene. Calcium carbide is commonly used in commercial fruit ripening despite health concerns.

Chloroacetophenone (CN gas) is commonly known as tear gas, a lachrymatory agent that causes severe eye irritation, tearing, and temporary blindness. LSD is a hallucinogenic drug, 'Dishlorodiethyl Sulphide' appears to be a misspelling of sulfur mustard (mustard gas), and TNT is an explosive. Tear gas is used for riot control and police operations.

Propane (boiling point -42°C) and butane (boiling point -0.5°C) both remain liquid at -88°C since this temperature is well below their boiling points. Methane would be gaseous at -88°C as its boiling point is -161.5°C, and ethane boils at -88.6°C, so it would be transitioning between states at this temperature.

By definition, hydrocarbons are organic compounds consisting ONLY of carbon and hydrogen atoms. This is a fundamental concept in organic chemistry - the prefix 'hydro-' refers to hydrogen, and '-carbon' refers to carbon. Oxygen, nitrogen, and carbon dioxide are not part of pure hydrocarbons.

Freon is the correct answer. It's a trade name for chlorofluorocarbon (CFC) refrigerants that were commonly used in refrigerators and air conditioning systems. Neon is used in lighting, crypton is not a real chemical (likely a distractor), argon is an inert gas used in welding and lighting, and ice is not a refrigerant but rather a cooling medium.

Carbon dioxide is used in fire extinguishers because it is heavier than air.