Name the element represented by the symbol $\mathrm{K}$. 

Name the element represented by the symbol $\mathrm{Pb}$.

Name the element represented by the symbol $\mathrm{Zn}$.

Name the element represented by the symbol $\mathrm{Br}$.

Name the element represented by the symbol $\mathrm{Cl}$.

Write the balanced chemical equation for the following word equation:

Potassium nitrate $\to$ Potassium nitrite $+$ Oxygen