Chemical BondinghardMCQ SINGLE

Drago's Rule explains why certain molecules possess bond angles close to . Why does the bond angle iChemical Bonding Chemistry Question

Question

Drago's Rule explains why certain molecules possess bond angles close to $90^\circ$. Why does the $H-P-H$ bond angle in phosphine ($PH_3$) approximate $90^\circ$ rather than the expected tetrahedral angle?

Answer: B

💡 Solution & Explanation

Drago's Rule states that elements of the 3rd period and below do not undergo hybridization when bonded to less electronegative atoms like Hydrogen. Because nearly pure $p_x$, $p_y$, and $p_z$ orbitals (which are $90^\circ$ apart) are used for bonding, the resulting bond angle in $PH_3$ is close to $90^\circ$.

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