The successive dissociation constants $K{a}_1$, $K{a}_2$ and $K{a}_3$ of ortho phosphorous acid $\left(H_{3}P{O}_3\right)$are

Ortho phosphorous acid is a polyprotic solvent. Higher order ionization constants ($K{a}_2$, $K{a}_3$) are smaller than the lower order ionization constant ($K{a}_1$) of a polyprotic acid.

The dissociation constant or acid strength of polyprotic acid decreases as protons are lost.

For $H_{3}P{O}_3$, the $K{a}_1>K{a}_2>K{a}_3$

Hence, the correct option is option 2) $1.6\times {10}^{-2}$, $7\times {10}^{-7}$, 0.