Question

Valence shell electron pair repulsion theory (VSEPR) provides a method for predicting the shape of molecules, based on the electron pair electrostatic repulsion.According to VSEPR model, molecules adopt geometries in which their valence electron pairs position themselves as far from each other as possible.The VSEPR model consider double and triple bonds to have slightly greater repulsive effects than single bonds because of the repulsive effect of `pi` electrons.how ever, the lone pair creates the maximum repulsive effect.
Incorrect order about bond angles is :
A. `H_2OgtH_2SgtH_2SegtH_2Te`
B. `C_2H_2gtC_2H_4gtCH_4gtNH_3`
C. `SF_6lt NH_3ltH_2OltOF_2`
D. `CIO_2 gt H_2Ogt H_2SgtSF_6`

Answer 1

Correct Answer - C
(A)According to VSEPR theory, as electronegativity of central atom decreases, bond angle decreases.So bond angle of `H_2O gt H_2S gt H_2Se gt H_2Te`
(B)`C_2H_2 gtC_2H_4 gt CH_4 gt NH_3`.In `NH_3` there is bp-lp repulsion so bond angle decreases to `107^@` from `109.5^@`
`{:(sp,sp^2,sp^3,sp^3),(180^@,120^@,109.5^@,107^@):}`
( C)The correct order is `{:(SF_6lt,OF_2lt,H_2Olt,NH_3),(90^@,102^@,104.5^@,107^@):}`
(D)`CIO_2 gt H_2O gtH_2S gtSF_6`

`{:(sp^2,sp^3,---,sp^3d^2),(~~117^@,104.5^@,92^@,90^@):}`