Write the electronic configurations of $\mathrm{C}$ and $\mathrm{H}$ atoms, and then calculate the total number of valence electrons in ${\mathrm{C}}_2{\mathrm{H}}_2$.

In methane molecule the number of $\mathrm{C}-\mathrm{H}$ bonds is $6$.

Write the correct form of the following statement:

Ionic bond is formed by sharing of a pair of electrons between two atoms.

Write the correct forms of the following statement:

Fluorine atom is more electronegative than $\mathrm{H}$ atom, therefore, the $\mathrm{H}-\mathrm{F}$ bond is formed by gain and loss of electrons.

Write the correct forms of the following statement:

In ${\mathrm{C}}_2{\mathrm{H}}_4$ the valency of $\mathrm{C}$ atom is $4$, and in ${\mathrm{C}}_2{\mathrm{H}}_2$ the valency of $\mathrm{C}$ atom is $2$.