Explanation

(d)
Given,
observed dipole moment = 1.03 D
Bond length of HCl molecule, d = 1.275 $\mathring{\mathrm{A}}$
$= \ 1.275 \times 10^{- 8}\ cm$
Charge of electron, $e^{-} = 4.8 \times 10^{- 10}\ esu$
Percentage ionic character = ?
Theoretical value of dipole moment = $e \times d$
$= 4.8 \times 10^{- 10} \times 1.275 \times 10^{- 8}\$esu.cm
$= 6.12 \times 10^{- 18}\$esu.cm
= 6.12 D
Percentage ionic character
$= \frac{observed\ dipole\ moment}{theoretical\ value\ of\ dipole\ moment} \times 100$
$\ = \frac{1.03}{6.12} \times 100 = 16.83\%$