Question

The ratio between radii of $He^{+}$ ion and $H$ atom is

• A. $1$
• B. $\frac{1}{2}$
• C. $\frac{3}{2}$
• D. $2$

Answer 1

Answer: (A)

Value of $Z$ for hydrogen = $1$
Value of $Z$ for helium = $2$
Value of $n$ for both is = $1$
$r_{H}=\frac{0.52\times1^{2}}{1} r_{He^{+}} =\frac{0.52\times1^{2}}{1}$
$\frac{r_{H}}{r_{He^{+}}}=1:1$ or $r_{He^{+}} :r_{H}=1:1$