Question

Among sulphurous acid and sulphuric acid,which is stronger?

Answer 1

Sulphuric acid is stronger than sulphurous acid because the presence of water in dilute sulphuric acid increases the hydrogen ion concentration. Hence it is a stronger acid than concentrated sulphuric acid which contains comparatively less water. 

Comments

H2SO4 is a stronger acid than H2SO3.
The oxidation state of S is more in H2SO4 which is +7 as compared to +4 in H2SO3.
Greater is the oxidation state of central atom, the more it attracts the electrons towards itself and also, more it stabilises the conjugate base.
Therefore,  H2SO4 is a stronger acid.