Statement I : Bond angle in NH3 is around 107o where as in other hydrides it is around 90oStatement II : Hybrid orbitals are involved in bonding  in NH3 where as pure p-orbitals in other hydrides

cosθ==ss-1=p-1p; θ in NH3 is 1070.  The calculated p- character  is around 75%.Thus the hybridisation in NH3 is sp3θ in PH3 is 93.60 , the calculated p- character  is around 97%.Thus we assume that pure p-orbitals participate in bonding in PH3,  AsH3 & SbH3.