Which of the following gases is responsible for the greenhouse effect?
A. Oxygen
B. Methane
C. Nitrogen
D. Argon
Answer: Option B
Solution (By JKSSB Mock Tests)
Methane (CH₄) is a potent greenhouse gas, absorbing infrared radiation. Oxygen and nitrogen are diatomic and do not absorb IR. Argon is a noble gas, inert. Greenhouse gases include CO₂, CH₄, N₂O, CFCs, H₂O vapor.
Explanation:
Plaster of Paris (CaSO₄·½H₂O) sets by rehydrating to gypsum (CaSO₄·2H₂O) when mixed with water: CaSO₄·½H₂O + 1½H₂O → CaSO₄·2H₂O. The interlocking crystals of gypsum provide hardness. It expands slightly on setting, making it ideal for casting. Dehydration is the opposite. Oxidation and carbonation are not involved.
Explanation:
The thermite reaction involves aluminum powder reacting with iron(III) oxide to produce molten iron and aluminum oxide (2Al + Fe₂O₃ → Al₂O₃ + 2Fe). It is highly exothermic and is used for welding railway tracks and repairing metal structures in the field.
Explanation:
Chlorination is a disinfection process. Chlorine reacts with water to form hypochlorous acid, which kills bacteria and viruses. It also provides residual protection in distribution pipes. Filtration removes particles; chlorine does not remove dissolved minerals or improve taste significantly; it can cause taste issues if excess.
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