Question

Radius of the second Bohr orbit of a singly ionised helium atom is

• A. $0.53A^o$
• B. $1.06A^o$
• C. $0.265A^o$
• D. $0.132A^o$

Answer 1

The correct option is B $1.06A^o$

Radius of nth Bohr orbit $r_n=\frac{0.529n^2}{Z}{A}^o$
For ionised Helium atom $Z=2$
Second Bohr orbit $n=2$
$⟹r_2=\frac{0.529\times 2^2}{2}=1.06A^o$