Question

Few pairs of molecule are given below. Which bond of the molecule of the pair is more polar?
(i) $H_{3}C-H,H_{3}C-Br$
(ii) $H_{3}C-N{H}_2,H_{3}C-OH$
(iii) $H_{3}C-OH,H_{3}C-SH$
(iv) $H_{3}C-Cl,H_{3}C-Br$

• A. $C-Br,C-N,C-O,C-Br$
• B. $C-Br,C-O,C-O,C-Cl$
• C. $C-Br,C-N,C-S,C-Cl$
• D. $C-Br,C-O,C-S,C-Br$

Answer 1

The correct option is B $C-Br,C-O,C-O,C-Cl$

Polarity is caused by a difference in electronegativity between two bonded atoms.

(i) Since $Br$ is more electronegative than $H$, $C-Br$ bond is more polar.

(ii) Since $O$ is more electronegative than $N$, $C-O$ bond is more polar.

(iii) Since $O$ is more electronegative than $S$, $C-O$ bond is more polar.

(iv) Since $Cl$ is more electronegative than $Br$, $C-Cl$ bond is more polar.