Which gas is known as 'marsh gas'? MCQ with Answer and Explanation

Explanation:
Stainless steel is an alloy of iron with chromium (minimum 10.5%), often nickel, and sometimes molybdenum. Chromium forms a passive oxide layer (Cr₂O₃) that prevents rusting. Brass is Cu + Zn. Bronze is Cu + Sn. Solder is Pb + Sn. Stainless steel is used in kitchen utensils, surgical instruments, and architecture. The most common type is 304 stainless (18% Cr, 8% Ni).

Explanation:
Temporary hardness is due to dissolved bicarbonates of Ca and Mg, which can be removed by boiling: Ca(HCO₃)₂ → CaCO₃↓ + H₂O + CO₂. Permanent hardness is caused by chlorides and sulfates of Ca and Mg, not removed by boiling. Sodium bicarbonate does not cause hardness. Methods to remove permanent hardness include treatment with washing soda (Na₂CO₃), ion exchange, or calgon.

Explanation:
Propane is an alkane with three carbon atoms: CH₃CH₂CH₃, formula C₃H₈. Methane: CH₄, Ethane: C₂H₆, Butane: C₄H₁₀. Propane is a component of LPG. Alkanes follow CnH₂n+2. For n=3, H=8. Propane is a gas at room temperature, liquefied under pressure. It is used as fuel for heating and cooking.