Mg (s) + H₂SO₄ (aq) → MgSO₄ (aq) + H₂ ↑ is the balanced chemical reaction. A balanced equation is the one in which the atoms of every element will be the same on both the sides of the equation.

After replacement, bulb glows in B as NaOH solution contains Na⁺ and OH⁻ ions, which are responsible for electrical conductivity.

(i)Rainbow is caused by scattering of sunlight by tiny water droplets, present in the atmosphere. (ii) A rainbow is always formed in a direction opposite to that of the Sun. (iii) The water droplets refract and scatter the incident sunlight, ...