Write the chemical formula of Potassium sulphate in a step-by-step manner.

Step 1 — Write each symbol with its valency

$\text{K}^{1+} \phantom{\nearrow} \text{SO}_4^{2-}$

Step 2 — Interchange the valencies

$\overset{\phantom{2}{1}}{\text{K}} \space {\searrow}\mathllap{\swarrow} \space \overset{2}{\text{SO}$4} \Rightarrow \underset{\phantom{1}{2}}{\text{K}} \space {\searrow}\mathllap{\swarrow} \space \underset{1}{\text{SO}4} \\[0.5em]

Step 3 — Write the interchanged number & hence the formula

Therefore, we get

Formula of Potassium sulphate : $\bold{K$2SO4}