Graham's law is applicable to: MCQ with Answer and Explanation

Explanation:
The combined gas law integrates Boyle's (P₁V₁ = P₂V₂), Charles' (V₁/T₁ = V₂/T₂), and Gay-Lussac's (P₁/T₁ = P₂/T₂) laws into one equation: P₁V₁/T₁ = P₂V₂/T₂ for a fixed amount of gas. It assumes ideal behavior. When one variable is constant, the respective individual law can be derived. For changing conditions, this combined form is useful. For n moles, PV = nRT.

Explanation:
Dalton's atomic theory (1808) provided a framework for the laws of chemical combination—conservation of mass, constant composition, and multiple proportions. The law of multiple proportions states that when two elements form more than one compound, masses of one that combine with fixed mass of the other are in small whole number ratios. Dalton proposed atoms combine in simple whole number ratios to form compounds.

Explanation:
Calcination involves heating an ore in limited supply or absence of air, often to convert carbonates/hydroxides to oxides and remove moisture or volatile impurities. Example: CaCO₃ → CaO + CO₂; Al(OH)₃ → Al₂O₃ + 3H₂O. Roasting is heating in excess air, usually for sulfide ores. Smelting uses reducing agents to obtain metal. Leaching uses chemicals.