The number of electrons in the valence shell of calcium is 

1. 6

2. 8

3. 2

4. 4

The brackett series of spectral lines arise when an electron in an excited hydrogen atom jumps from an energy level

1. n=5 to n=1

2. n=5 to n=3

3. n=5 to n=4

4. n=5 to n=2

What is the ratio of the time period of revolution of electron He⁺ ion sample in the orbit where the path length is three time the de-broglies wavelength to the time period of revolution in the ground state –

1. 27:1

2. 1:27

3. 9:8

4. 8:9

The ratio of the wavelengths of the last lines of the Balmer and Lyman series is-

1. 4:1

2. 27:5

3. 3:1

4. 9:4

The energy of the emitted photon when an electron in $B{e}^{3+}$ ion returns from n=2 level to the ground state is 

1. 2.616 x 10^-17J

2. 26.16 x 10^-17J

3. 261.6 x 10^-18J

4. 2616 x 10^-17J

The accelerating potential to be imparted to a beam of electrons to give an effective wavelength of 2.42 nm is 

1. 2.56V

2. 3.42V

3. 0.256V

4. 0.342V

The splitting of spectral lines in a magnetic field, arising out of the orbital motion of electrons only and the further splitting due to spin motion are respectively called

1. Zeeman and Stark effects

2. Zeeman and anomalous Zeeman effects

3. Stark and Zeeman effects

4. Zeeman and Kerr effects

A photon of wavelength 300 nm causes the emission of two photons. If the wavelength of one of them is 700 nm. What is the wavelength of the other photon?

1. 525 nm

2. 600 nm

3. 450 nm

4. 300 nm

The electronic transition in the hydrogen atom that emits maximum energy is:

1. 2 $\to$ 1

2. 1 $\to$ 4

3. 4 $\to$ 3

4. 3 $\to$ 2

The spectrum of He-atom may be considered similar to the spectrum of - 

1. H

2. Li⁺

3. Na

4. He⁺