Give the classification of acids on the basis of $pK_{a}$ value.

(N/A) The strength of an acid is inversely proportional to its $pK_{a}$ value,meaning a smaller $pK_{a}$ indicates a stronger acid.
$1$. Strong acids: $pK_{a} < 1$.
$2$. Moderately strong acids: $1 < pK_{a} < 5$.
$3$. Weak acids: $5 < pK_{a} < 15$.
$4$. Extremely weak acids: $pK_{a} > 15$.