Question

Calculate the angular orbital momentum of the orbiting electron in the fifth orbit of an atom.

• A. $5.25\times {10}^{34}\text{kg}{\text{m}}^2{\text{s}}^{-1}$
• B. $5.25\times {10}^{-43}\text{kg}{\text{m}}^2{\text{s}}^{-1}$
• C. $5.25\times {10}^{-34}\text{kg}{\text{m}}^2{\text{s}}^{-1}$
• D. $6.25\times {10}^{-34}\text{kg}{\text{m}}^2{\text{s}}^{-1}$

Answer 1

The correct option is C $5.25\times {10}^{-34}\text{kg}{\text{m}}^2{\text{s}}^{-1}$

According to Bohr's second postulate, the angular orbital momentum of a revolving electron is given by,

$L=\frac{nh}{2\pi }$

So, for $n=5$, we have,

$L=\frac{5\times 6.6\times {10}^{-34}}{2\pi }=5.25\times {10}^{-34}\text{kg}{\text{m}}^2{\text{s}}^{-1}$

Hence, option $\left(C\right)$ is the correct answer.