MHTCET 25 Apr 2025 Shift 2 Paper

Concept:Polarity of a molecule depends on its net dipole moment, which is the vector sum of all bond dipoles and lone-pair contributions.Explanation:All the given molecules contain polar bonds, but their shapes decide the net dipole moment.In $\mathrm{NH}_3$, the three $\mathrm{N}-\mathrm{H}$ bond dipoles and the lone pair on nitrogen add up in the same direction, giving a high resultant dipole moment.In $\mathrm{NF}_3$, the lone pair opposes the three $\mathrm{N}-\mathrm{F}$ bond dipoles, resulting in a much smaller dipole moment.$\mathrm{H}_2 \mathrm{~S}$ has a bent shape, but its bond dipoles are weaker and cancel more than in ammonia.$\mathrm{CHCl}_3$ has a moderate dipole moment, still lower than that of ammonia.Thus, $\mathrm{NH}_3$ has the highest dipole moment and is the most polar molecule among the options.Answer:B. $\mathrm{NH}_3$