Write the equation and balance them.

Silver oxide+Hydrogen peroxide$\to$Silver+Water+Oxygen

Write the equation and balance them.

Calcium carbonate+Hydrochloric acid$\to$Calcium chloride+water+Carbon dioxide

Write the valency of carbon in ${\mathrm{CH}}_4$.

Write the valency of phosphorus in ${\mathrm{PH}}_3$.

Write the valency of sulphur in ${\mathrm{SF}}_6$.

Write the valency of fluorine in ${\mathrm{CaF}}_2$.

Write the valency of nitrogen in ${\mathrm{N}}_2{\mathrm{O}}_3$.

An element 'X' has a valency 1. Write the chemical formula of its phosphide.