The formula of bleaching powder is: MCQ with Answer and Explanation

Explanation:
Ozone (O₃) is a powerful disinfectant that decomposes to oxygen, leaving no toxic residues or taste. Chlorination can form carcinogenic trihalomethanes (THMs) with organic matter. However, ozone is more expensive, must be generated on-site, and leaves no residual protection in distribution system, often requiring a small chlorine dose. Ozonation also removes color and odor. Both kill bacteria and viruses.

Explanation:
Across a period, the number of electron shells remains the same, but the nuclear charge (protons) increases. The added electrons enter the same valence shell, so the effective nuclear attraction on the electrons increases, pulling them closer and shrinking the atomic radius. Down a group, radius increases due to addition of shells. Electron-electron repulsion alone does not account for the trend. Atomic mass generally increases across a period.

Explanation:
Charles' law: V ∝ T at constant pressure and for a fixed mass (n constant). If pressure or amount changes, the relationship does not hold. The temperature must be in Kelvin.