Bohr's Postulates

Q. An electron in Bohr's hydrogen atom has an energy of $-3.4eV$. The angular momentum of the electron is

1. $\frac{h}{\pi }$
2. $\frac{h}{2\pi }$
3. $\frac{3h}{2\pi }$
4. $\frac{h}{\pi }$

Q.

The difference between the apparent frequency of a source of sound as perceived by an observer during its approach and recession is 2% of the natural frequency of the source. If the velocity of sound in air is 300 m/sec, the velocity of the source is (It is given that velocity of source << velocity of sound)

1. 6m/sec

2. 3m/sec

3. 1.5m/sec

4. 12m/sec

Q. According to Bohr's postulate, electrons revolve around the nucleus in certain definite circular paths called stationary orbits in which they do not radiate energy.

1. False
2. True

Q. Which of these are Bohr's postulates?

1. In an atom, the electrons revolve around the nucleus in certain definite circular paths called stationary orbits in which they do not radiate energy.
2. Electron revolves around nucleus only in those orbits for which the angular momentum is an integral multiple of $\frac{h}{2\pi }$
3. Atoms with more than 1 electron will have subshells present in their permissible orbits.
4. An electron present in an atom can move from a lower energy level to a level of higher energy by absorbing the appropriate energy.

Q. The magnetic moment $\left(\mu \right)$ of an electron revolving around the nucleus, varies with principal quantum number $n$ as,

1. $\mu \propto \frac{1}{n^2}$
2. $\mu \propto n$
3. $\mu \propto \frac{1}{n}$
4. $\mu \propto n^2$