\(\rm K_{a_1}, \ K_{a_2}\ and \ K_{a_3}\) are the respective ionisation constants for the following reactions.
H2S \(\rightleftharpoons\) H+ + HS–
HS– \(\rightleftharpoons\) H+ + S2–
H2S \(\rightleftharpoons\) 2H+ + S2–
The correct relationship between \(\rm K_{a_1}, \ K_{a_2}\ and \ K_{a_3}\) is
1
\(\rm K_{a_3} = K_{a_1}\times K_{a_2}\)
2
\(\rm K_{a_3} = K_{a_1}+K_{a_2}\)
3
\(\rm K_{a_3} = K_{a_1}-K_{a_2}\)
4
\(\rm K_{a_3} = K_{a_1}/K_{a_2}\)