JEE MAIN - Chemistry (2024 - 5th April Morning Shift - No. 27)
The value of Rydberg constant $$(R_H)$$ is $$2.18 \times 10^{-18} \mathrm{~J}$$. The velocity of electron having mass $$9.1 \times 10^{-31} \mathrm{~kg}$$ in Bohr's first orbit of hydrogen atom = ________ $$\times 10^5 \mathrm{~ms}^{-1}$$ (nearest integer).
Answer
22
Explanation
$$\begin{aligned}
& \text { K.E. }=R_H \cdot \frac{z^2}{n^2}=\frac{1}{2} m v^2 \\
& v^2=\frac{2 \times 2.18 \times 10^{-18}}{9.1 \times 10^{-31}} \times \frac{1}{1}=0.479 \times 10^{13} \\
& v=21.88 \times 10^5 \mathrm{~m} / \mathrm{s}
\end{aligned}$$
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