JEE MainChemistryp Block Elements (Group 15, 16, 17 & 18)
Consider the hydrides of Group 15 elements, EH ₃ ( E = N , P , As , Sb , Bi ). The variation of three different properties (X, Y, and Z) of these hydrides is plotted against the atomic number of the central atom E . The observed trends are as follows: Curve X: Decreases continuously from NH ₃ to BiH ₃ . Curve Y: Is anomalously high for NH ₃ , drops sharply for PH ₃ , and then increases continuously up to BiH ₃ . Curv
Options
- AX = Reducing character, Y = Boiling point, Z = Thermal stability
- BX = Thermal stability, Y = Lewis basicity, Z = Reducing character
- CX = Lewis basicity, Y = Boiling point, Z = Reducing character
- DX = Boiling point, Y = Reducing character, Z = Thermal stability
Correct answer
C. X = Lewis basicity, Y = Boiling point, Z = Reducing character
Step-by-step solution
For Group 15 hydrides ( EH ₃ ): Curve X represents a property that decreases continuously down the group. Lewis basicity decreases from NH ₃ to BiH ₃ because the electron density on the central atom decreases as its size increases. Thermal stability and bond angle also follow this trend. Curve Y represents a property that is anomalously high for NH ₃ , lowest for PH ₃ , and then increases. This corresponds to the boiling point. The boiling point of NH ₃ is unusually high due to strong intermolecular hydrogen bondin