`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_3)=([H^+]^2[S^(2-)])/([H_2S])=([H^+][HS])/([H_2S])xx([H^+][S^(2-)])/([HS^-])`
`=K_(a_1) xx K_(a_2)`