Question

The radius of the first Bohr orbit of a hydrogen atom is $0.529\mathring{A}.$ The radius of the third orbit of $H{e}^{+}$ will be:

• A. $8.46\mathring{A}$
• B. $0.705\mathring{A}$
• C. $1.59\mathring{A}$
• D. $2.38\mathring{A}$

Answer 1

The correct option is D $2.38\mathring{A}$

According to Bohr model, radius of hydrogen like-atom:

$\left(r_n\right)=\frac{0.529\times n^2}{Z}\mathring{A}$

where $n=$ number of orbit

$Z=$ atomic number

$r_3=\frac{0.529\times (3{)}^2}{2}=2.38\mathring{A}$