HF < HCl < HBr < HI (on moving top to bottom, bond dissociation energy decreases, so acidic strength increases).

B < C < O < N (on moving left to right, Zeff increases, so first ionization enthalpy increases ; N > O because N is half filled).

CO2 < SiO2 < SnO2 < PbO2 (on moving top to bottom, + 4 oxidation state becomes less stable due to inert pair effect). So oxidising power increases.

Since, (1), (3) and (4) are correct, so (2) is the answer.

In hydrides of 15th group elements, the basic strength decreases down the group and the correct order is :

SbH3 < AsH3 < PH3 < NH3