Its reversible reaction or notWatch
(acid 1) . . (base 2) . . . . (base 1) . . (acid 2)
Hydrogen sulphide acts as a weak acid in water, so donates a proton to the water molecule (which then becomes an acid - the hydronium ion)
It is reversible because it is an acid-base reaction and most are reversible.
(and theoretically all reactions are?)
Why in marking scheme they just state a single arrow ? Does strong acids have reversible reaction too ? Equilibrium sign should be written or not for the chemical equation of strong acid
The markscheme probably had a single arrow because the question asked specifically for the ionisation of H2S. I would say it's correct to put either in that case. I don't think it's something that would be penalised, but I may be wrong.