`K_(a1)`,`K_(a2)`and `K_(a3)` are the respective ionisation constants for the following reactions.
`H_(2)ShArrH^(+)+HS^(-)`,`HS^(-)hArrH^(+)S^(-2)`
`H_(2)ShArr2H^(+)+S^(2-)`
The correct relationship between `K_(a1)`,`K_(a2)`and `K_(a3)` is

Options

A. `K_(a_(3))=K_(a_(1))xxK_(a_(2))`
B. `K_(a_(3))=K_(a_(1)) + K_(a_(2))`
C. `K_(a_(3))=K_(a_(1)) - K_(a_(2))`
D. `K_(a_(3))=K_(a_(1)) // K_(a_(2))`

Answer

A

Explanation

`K_(a_(1))=([H^(+)][HS^(-)])/([H_(2)S]),K_(a_(2))=([H^(+)][S^(2-)])/([HS^(-)]), K_(a_(3))=([H^(+)]^(2)[S^(2-)])/([H_(2)S])`
Obviously, `K_(a_(3))=K_(a_(1))xxK_(a_(2))`.