Explain: ${\mathrm{BeCl}}_2$ is covalent while ${\mathrm{MgCl}}_2$ is ionic.

Explain: Lithium floats on water while sodium floats and catches fire when put in water.

Write balanced chemical equation for the given statement: ${\mathrm{CO}}_2$ is passed into concentrated solution of $\mathrm{NaCl}$, which is saturated with ${\mathrm{NH}}_3$.

Write balanced chemical equation for $50\%$ solution of sulphuric acid is subjected to electrolyte oxidation and the product is hydrolyzed.

Identify the odd one out.