Import Question JSON

$\text{Hint: Reducing character} \propto \frac{1}{\text{E-H}} \text{ bond dissociation enthalpy}$ $\text{Explanation:}$ $\text{a. Thermal stability decreases gradually from NH}_3 \text{ to BiH}_3\text{. The size of the central atom increases from N to Bi, therefore, the tendency to form a stable covalent bond with small hydrogen atoms decreases.}$ $\text{As the bond length increases, the bond strength decreases and therefore, thermal stability decreases.}$ $\text{b. The size of the central atom increases from N to Bi, therefore, the tendency to form a stable covalent bond with small hydrogen atoms decreases. As the bond length increases, the bond strength decreases and therefore, bond dissociation enthalpy decreases.}$ $\text{c. Reducing character} \propto \frac{1}{\text{E-H}} \text{ bond dissociation enthalpy}$ $\text{The size of the central atom increases from N to Bi, therefore, the tendency to form a stable covalent bond with small hydrogen atoms decreases.}$ $\text{As the bond length increases, the bond strength decreases and therefore bond dissociation enthalpy decreases.}$ $\text{Hence, the correct reducing character is}$ $\text{NH}_3 < \text{PH}_3 < \text{AsH}_3 < \text{SbH}_3 < \text{BiH}_3$ $\text{d. The basic character decreases from NH}_3 \text{ to BiH}_3\text{. The basic nature is due to the presence of lone pair of electrons on the central atom. NH}_3 \text{ is the strongest electron-pair donor due to its small size as the electron density of the electron pair is concentrated over a small region.}$ $\text{As the size increases the electron density gets diffused over a large region and hence the ability to donate the electron pair (basic nature) decreases.}$