Question

If velocity of an electron in 1st orbit of H atom is V, what will be the velocity in 3rd orbit of Li${}^{2+}$ ?

• A. $V$
• B. $\frac{V}{3}$
• C. $3V$
• D. $9V$

Answer 1

The correct option is A $V$

$V$ of H${}_2^{\oplus }$ = $\frac{2\pi Z{e}^2}{nh}$or V $\alpha$ $\frac{Z}{n}$
$\therefore$ V H${}_2^{\oplus }$ $\alpha$ 1 (Z = 1, n = 1)
$V$ of Li${}^{2+}$ $\alpha$ $\frac{3}{3}$ $\alpha$ 1 (Z = 3, n = 3)
Therefore, velocity of e${}^{-}$ in the third orbit of Li${}^{2+}$ is the same velocity of an e${}^{-}$ in the first orbit of H atom