The correct decreasing order of boiling points for the hydrides of group 15 elements is: — p Block Elements Chemistry Question

💡 Solution & Explanation

Boiling points generally increase down the group due to increasing van der Waals forces. However, $NH_3$ has an exceptionally higher boiling point than $PH_3$ and $AsH_3$ due to strong intermolecular hydrogen bonding. The order is $BiH_3$ (290 K) $>$ $SbH_3$ (254.6 K) $>$ $NH_3$ (238.5 K) $>$ $AsH_3$ (210.6 K) $>$ $PH_3$ (185.5 K).