Question

The radius of the third orbit of a hydrogen like species is $4.5r_0$, where $r_0$ is the radius of the first orbit of a hydrogen atom. What is the atomic number of the hydrogen like species?

• A. 1
• B. 2
• C. 3
• D. 4

Answer 1

The correct option is B 2

We know, for a hydrogen like species
$r=\frac{n^2}{Z}{r}_0$
So according to the question,
$\Rightarrow 4.5r_0=\frac{9}{Z}{r}_0$
$\Rightarrow Z=2$