The ozone layer is found in which layer of the atmosphere? MCQ with Answer and Explanation

Explanation:
Hydrochloric acid (HCl) is a strong acid because it completely dissociates into H⁺ and Cl⁻ ions in aqueous solution. Acetic, citric, and carbonic acids are weak acids as they only partially dissociate in water, establishing an equilibrium between the unionized molecules and their ions.

Explanation:
Camphor sublimes—it directly changes from solid to vapor on heating without passing through the liquid phase. Other sublimable solids include naphthalene, iodine, ammonium chloride, and dry ice (solid CO₂). Sodium chloride, sugar, and sand melt or decompose on strong heating. Sublimation is used to separate sublimable substances from non-sublimable impurities. The process requires careful heating.

Explanation:
Permanent hardness (due to CaSO₄ etc.) can be removed by adding Na₂CO₃, which precipitates CaCO₃. Boiling only removes temporary hardness. Ion exchange and calgon also work.