Find the correct statements related to group 15 hydrides. A....

Statement A: The reducing nature of group 15 hydrides depends on the E-H bond strength. As the size of the central atom increases down the group, the E-H bond dissociation enthalpy decreases. Hence, the reducing character increases from NH$_3$ to BiH$_3$. This statement is correct.

Statement B: The basic character or the tendency to donate a lone pair of electrons depends on the electron density on the central atom. As the size of the central atom increases down the group, the electron density decreases. Thus, the basicity decreases from NH$_3$ to BiH$_3$. This statement is correct.

Statement C: Due to the decrease in E-H bond dissociation enthalpy down the group, the thermal stability of the hydrides decreases from NH$_3$ to BiH$_3$. This statement is correct.

Statement D: The H-E-H bond angle decreases down the group because the electronegativity of the central atom decreases and the size increases, causing the bond pairs to move further away from the central atom. This decreases the bond pair-bond pair repulsion. The bond angles are NH$_3$ ($107.8^{\circ}$), PH$_3$ ($93.6^{\circ}$), AsH$_3$ ($91.8^{\circ}$), and SbH$_3$ ($91.3^{\circ}$). This statement is correct.

All statements A, B, C, and D are correct.

Answer: A, B, C and D