The ion that is isoelectronic with CO is-

1. CN^-

2. O₂⁺

3. O₂^-

4. N₂⁺

If uncertainity in position and momentum are equal, the uncertainty in velocity is:

1. $\sqrt{h/2\mathrm{\pi }}$

2. $\frac{1}{2m}\sqrt{h/\mathrm{\pi }}$

3. $\sqrt{h/\mathrm{\pi }}$

4. None

When the atoms of gold sheet are bombarded with a beam of $\alpha$ -particles, only a few a-particles get deflected where as most of them go straight undeflected. This is because:

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

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 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

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 frequency ratio between violet (400nm) and red (750nm) radiations in the visible spectrum, is-

1. 8/15

2. 4/15

3. 15/8

4. None of these

The total spin resulting for a 3d⁷ configuration is 

1. 3/2

2. 1/2

3. 2

4. 1