Which of the following contains both covalent and ionic bonds?

Identify the correct thermal stability orders among the following:
$(a) BeSO_4 < MgSO_4 < CaSO_4 < SrSO_4 < BaSO_4$
$(b) HF > H_2O > NH_3 > CH_4$
$(c) NH_3 > PH_3 > AsH_3 > SbH_3$
$(d) LiCl > BeCl_2 > BCl_3 > CCl_4$
$(e) Na_2CO_3 > MgCO_3 > Al_2(CO_3)_3$
$(f) Li_2CO_3 < Na_2CO_3 < K_2CO_3 < Rb_2CO_3 < Cs_2CO_3$

Which of the following molecules or ions is not possible?

Sulphuric acid $(H_2SO_4)$ provides an example of:

Choose the incorrect order of bond length $-$

Which of the following pairs have the same bond angles?
$(a) BF_3, BCl_3$
$(b) PO_4^{3-}, SO_4^{2-}$
$(c) BF_3, PF_3$
$(d) NO_2^+, N_2O$
$(e) N_3^-, NO_2$
Select the correct option: