The following are some statements related to group 15 hydridesi. Reducing property increases from NH3 to BiH3ii. Tendency to donate lone pair decreases from NH3 to BiH3iii. Thermal stability of hydrides decreases from NH3 to BiH3iv. Bond angle decreases from NH3 to BiH3The correct statements are:

The stability of hydrides decreases from NH3​  to BiH3​ due to increase in bond length between two atoms  Down the group size increases and overlap decreases so the bond strength increases. Hence their bond dissociation enthalpy decreases.Consequently, the reducing character of the hydrides increases.Ammonia is only a mild reducing agent while BiH3​ is the strongest reducing agent amongst all the hydrides. Basicity also decreases in the order NH3​>PH3​>AsH3​>SbH3​>BiH3​.Down the group size increases and the lone pair got stabilized on the big surface area of atom. Bond angle decreases from NH3​ to BiH3​ as bondpair-bond pair repulsions decreases.Hence all the statements are correct.