Question

The radius of the Bohr's orbit in ground state of hydrogen atom is 0.5Å. The radius of the orbit of the electron in the third excited state of He⁺ will be-

• A. 8Å
• B. 0.5Å
• C. 4Å
• D. 0.25Å

Answer 1

Answer: (C)

4Å

Answer 2

r µ $\frac{n^{2}}{Z}$

where, n = 4, Z = 2

$\frac{r_{1}}{r_{2}} = \frac{n_{1}^{2}Z_{2}}{Z_{1}n_{2}^{2}} = \frac{1^{2} \times 2}{1 \times 4^{4}}$

r₂ = 8r₁ = 4Å