Question

If in the Bohr's model for unielectronic atom, the time period of revolution is represented as $T_{n,z}$, where, n represents the shell number and $Z$ represents the atomic number then, the value of $T_{1,2}:T_{2,1}$ will be:

• A. 8 : 1
• B. 1 : 8
• C. 1 : 1
• D. 1 : 32

Answer 1

The correct option is D 1 : 32

$T\propto \frac{n^3}{Z^2}$

$T_{1,2}\propto \frac{1}{4}$ since $n=1$ and $Z=2$
$T_{2,1}\propto \frac{8}{1}$ since $n=2$ and $Z=1$

$\frac{T_{1,2}}{T_{2,1}}=\frac{1}{4}\times \frac{1}{8}=\frac{1}{32}$