Calculate and write the valency of the following element.

Zinc in zinc oxide.

Formula: $\mathrm{ZnO}.$

Work and make a formula for the following:

Copper(II)chloride. 

Work and make a formula for the following:

Aluminium oxide.

Work and make a formula for the following:

Ferric oxide.

Work and make a formula for the following:

Magnesium nitride.

Work and make a formula for the following:

Barium thiosulphate.

Write the name for the following:

$\mathrm{Ba}{\left(\mathrm{OH}\right)}_2$

Write the name for the following:

${\mathrm{Fe}}_2{\mathrm{O}}_3.$

Write the name for the following:

${\mathrm{Ag}}_2\mathrm{S}$