Find the correct statements related to group 15 hydrides.
A. Reducing nature increases from NH$$_3$$ to BiH$$_3$$
B. Tendency to donate lone pair of electrons decreases from NH$$_3$$ to BiH$$_3$$
C. The stability of hydrides decreases from NH$$_3$$ to BiH$$_3$$
D. HEH bond angle decreases from NH$$_3$$ to SbH$$_3$$ (E = Elements of group 15)
Choose the correct answer from the options given below :

The reducing nature of Group 15 hydrides increases from (NH_3) to (BiH_3) because the (E-H) bond strength decreases down the group due to increasing atomic size and poorer orbital overlap. Hence, the hydrides release hydrogen more readily.

Therefore,

$$\boxed{\text{Statement A is correct}.}$$

The tendency to donate the lone pair of electrons decreases from (NH_3) to (BiH_3). As the size of the central atom increases, the lone pair occupies a larger orbital and becomes less available for donation, resulting in decreased basicity.

Therefore,

$$\boxed{\text{Statement B is correct}.}$$

The stability of the hydrides decreases down the group because the (E-H) bond becomes progressively weaker with increasing atomic size.

Therefore,

$$\boxed{\text{Statement C is correct}.}$$

The (H-E-H) bond angle decreases from (NH_3) to (SbH_3). While (NH_3) has a bond angle of about (107^\circ), the heavier hydrides show reduced hybridization and the bond angles approach (90^\circ).

Therefore,

$$\boxed{\text{Statement D is correct}.}$$

Hence, all four statements are correct.

$$\boxed{\text{Correct Answer: A, B, C and D}.}$$