Question

Speed of an electron in Bohr's $7^{\text {th }}$ orbit for Hydrogen atom is $36 \times 10^6 m / s$. The corresponding speed of the electron in $3^{\text {rd }}$ orbit, in $m / s$ is :

• A. $\left(3.6 \times 10^6\right)$
• B. $\left(7.5 \times 10^6\right)$
• C. $\left(1.8 \times 10^6\right)$
• D. $\left(8.4 \times 10^6\right)$

Answer 1

Answer: (D)

$\left(8.4 \times 10^6\right)$

Answer 2

Vn​∝nZ​
Z=1,
∴Vn​∝n1​
∴V7​V3​​=37​
∴V3​=37​V7​
=37​×3.6×106m/s
=8.4×106m/s