Metal $\mathrm{M}$ forms a chloride with the formula ${\mathrm{MCl}}_2$. What type of bond is in ${\mathrm{MCl}}_2$. Write the formula of the compound when $\mathrm{M}$ combines with sulphur, oxygen and nitrogen.

Why the mass of an atom is concentrated inside the nucleus of the atom.

Explain the following:

Atoms combine by transfer and sharing of electron(s).

An element has atoms with different mass number. Explain it.

Carbon- $12$ and carbon- $14$ both show similar chemical properties. Explain it.

The characteristic of an electrovalent compound is that:

When a metal atom becomes an ion:

Identify the following reactions as either oxidation or reduction:

$\mathrm{O}+2{\mathrm{e}}^{-}\to {\mathrm{O}}^{2-}$

$\mathrm{K}-{\mathrm{e}}^{-}\to {\mathrm{K}}^{+}$