Question

Choose the correct option for the below-given statements.
Statement I: In Bohr’s model, the velocity of electrons increases with a decrease in the positive charge of the nucleus as electrons are not held tightly.

Statement II: Velocity decreases with an increase in principal quantum number.

• A. Statement I is correct & Statement II is correct
• B. Statement I is correct & Statement II is incorrect
• C. Statement I is incorrect & Statement II is incorrect
• D. Statement I is incorrect & Statement II is correct

Answer 1

The correct option is D

Statement I is incorrect & Statement II is correct

Bohr's law describe the structure of atoms especially that of hydrogen atom proposed by the Danish physics Neil's Bohr in $1913$. The Bohr model is one of the classical model to describe the velocity and radius of electron for hydrogen and hydrogen like species in quantum mechanical description.

Statement I:

The velocity of the electron, according to Bohr's law

Where, ${\mathrm{V}}_{\mathrm{o}}=2.18\times {10}^6\times (\mathrm{Z}/\mathrm{n})\to \left(\mathrm{i}\right)$

where, $\mathrm{Z}$ is atomic number corresponds to positive charge of the hydrogen like species

$\mathrm{n}$ is principal quantum number

So, as $\mathrm{Z}$ decreases, ${\mathrm{V}}_{\mathrm{n}}$ also decreases

Hence, velocity of the electron increases as the charge positive charge increases.

Hence, Statement I is incorrect,

Statement II:

From equation ($\mathrm{i}$), As the value of $\mathrm{n}$ decreases, velocity will decrease accordingly.

Hence, Statement II is correct

Therefore, option d is correct