Question

In which of the following arrangements, the sequence is not strictly according to the property written against it ?

(a) CO₂ < SiO₂ < SnO₂ < PbO₂ : increasing oxidising power

(b) HF < HCl < HBr < HI : increasing acid strength

(c) NH3 < PH₃ < AsH₃ < SbH₃ : increasing basic strength

(d) B < C < O < N : increasing first ionization enthalpy

Answer 1

(c) : In group15 hydrides, the basic character decreases on going down the group due to decrease in the availability of the lone pair of electrons because of the increase in size of elements from N to Bi. Thus, correct order of basicity is NH₃ > PH₃ > AsH₃ > SbH₃.