(i) 2Al + 3H₂SO₄ → Al₂(SO₄)₃ + 3H₂ (ii) 2AlCl₃ + 3Ca(OH)₂ → 2Al(OH)₃ + 3CaCl₂ (iii)2KClO₃ → 2KCl + 3O₂ (iv) Mg + H₂O → ...

You must know that – chlorine gas reacts with dry Ca(OH)₂ to form bleaching powder. Ca(OH)₂ + Cl₂ → CaOCl₂ + H₂O

In halogens, the electronegativity decreases down the group due to increase in atomic radius and decrease in tendency to gain electron.

Fluorine has the highest electronegativity. As a fluorine is the smallest and first element of its group. So, down the group of electro-negativity decreases due to increase atomic size.

Lactic acid (C₃H₆O₃) is formed when we respire anaerobically. Condition is that, when the heart and lungs cannot work fast enough to provide enough oxygen around the body to breakdown the glucose.