The rate of diffusion of a gas is: MCQ with Answer and Explanation

Explanation:
Neutralization is the reaction of an acid and a base to form salt and water. HCl (acid) + NaOH (base) → NaCl (salt) + H₂O. Option A is combination; C is decomposition; D is displacement.

Explanation:
A decomposition reaction is one where a single compound breaks down into two or more simpler substances. Heating potassium chlorate (KClO₃) breaks it down into potassium chloride and oxygen gas. A is combination, C is displacement, and D is double displacement.

Explanation:
Burning of magnesium ribbon produces a new substance, magnesium oxide (MgO), and releases heat and light, which are indicators of a chemical change. Melting, dissolving, and boiling are physical changes because the chemical composition remains unchanged. Chemical changes are generally irreversible.