The following are some statements related to VA group hydrides 

I : Reducing property increases from NH₃ to BiH₃ 

II : Tendency to donate lone pair decreases from NH₃ to BiH₃ 

III : Ease of replacing H with Cl decreases from NH₃ to BiH₃ 

IV :  Ease of formation of hydrides decreases from NH₃ to BiH₃ 

The correct statements are : 

(I) The reducing property of the hydrides of VA group increases from NH_3​ to BiH_3​ as M−H bond length increases.
(Where, M=N, P As, Sb,Bi )
NH_3​<PH₃​<AsH₃​<SbH₃​<BiH_3​
(II) The tendency to donate lone pair or basic strength decreases from NH₃​ to BiH_3​.
NH₃​>PH₃​>AsH_3​>SbH₃​>BiH_3​
(III) Thermal stability of VA group hydrides decreases from NH₃​ to BiH₃​.
NH₃​>PH₃​>AsH₃​>SbH₃​>BiH_3​
(IV) Bond angle of VA group hydrides decreases from NH3​ to BiH3​
NH₃​>PH_3​>AsH_3​>SbH₃​>BiH₃​