Question

Which transition in $L{i}^{2+}$ would have the same wavelength as the $2\to 4$ transition in $H{e}^{+}$ ion?

• A. $4\to 2$
• B. $2\to 4$
• C. $3\to 6$
• D. $6\to 2$

Answer 1

Answer: (C)

${\left(H{e}^{+}\right)}_{2\to 4}={\left(L{i}^{2+}\right)}_{n_4\to n_3}$
$\therefore \frac{Z_1}{Z_2}=\frac{n_2}{n_4}=\frac{n_1}{n_3}$
or $\frac{2}{3}=\frac{2}{n_4}=\frac{4}{n_3}$
$\therefore n_4=3$ and $n_3=6$
$\therefore$ Transition in $L{i}^{2+}$ ion $=3\to 6$