Question

If the radius of the first orbit of hydrogen atom is $5.29 \times 10^{-11} \,m$, the radius of the second orbit will be

• A. $21.16 \times 10^{-11}$ metre
• B. $15.87 \times 10^{-11}$ metre
• C. $10.58 \times 10^{-11}$ metre
• D. $2.64 \times 10^{-11}$ metre

Answer 1

Answer: (A)

Radius of $n^{\text {th }}$ orbit $=n^{2} r_{0}$
Radius of $2^{\text {nd }}$ orbit $=4 r_{0}$
$\left[r_{0} \approx 5.3 \times 10^{-11} m \right]$
$\therefore$ Hence radius needed $\approx 21.16 \times 10^{-11} m$