What is the number of electrons in ₁₉ K with quantum numbers n=3 and l=0?

1. Two (2)

2. One (1)

3. Four (4)

4. Three (3)

The ratio of the difference in energy between the first and second Bohr orbit of H to that between the second and the third Bohr orbit is 

1. 1/2

2. 1/3

3. 4/9

4. 27/5

The number of orbitals that are possible at the L-energy level is

1. 2

2. 4

3. 6

4. 1

The radius of second stationary orbit in Bohr's atom is R. The radius of 3^rd orbit will be:-

1. 9R

2. R/4

3. 9R/4

4. 2R

Which of the following is not correctly matched?

1. Energy associated with Bohr's orbit  \(E =\dfrac{-2.18 \times 10^{-18} \times Z^{2}}{n^{2}}\)

2. Energy gap between two orbits \(\Delta E=-h c Z^{2} R_{H}\left[\frac{1}{n_{1}{ }^{2}}-\frac{1}{n^{2}{ }_{2}}\right]\)

3. Kinectic energy of the ejected electron \(hv = hv_0 + \dfrac{1}{2}mv^2\)

4. Energy of one mole of photons \(E = N_0hv/C\)

If the velocity of a particle is reduced to 1/3^rd, then percentage increase in its de-broglie wavelength will be:-

1. 100%

2. 200%

3. 50%

4. 33.33%

The magnetic moment order is correctly given in 

1. Fe²⁺ < Fe³⁺ < Mn⁴⁺ < Cr³⁺

2. Cr³⁺ = Mn⁴⁺ < Fe²⁺ < Fe³⁺

3. Cr³⁺ = Mn⁴⁺ < Fe³⁺ < Fe²⁺

4. Fe²⁺ < Cr³⁺ < Fe³⁺ < Mn⁴⁺

Bohr's model is not valid for:-

1. H-atom

2. D-atom

3. T-atom

4. He-atom

The maximum wavelength in the Lyman series of He⁺ ion is-

1. 3R

2. 1/3R

3. 1/R

4. 2R

An atom having mass number 13 has 7 neutrons. What is the atomic number of the atom?

1. 6

2. 7

3. 4

4. 5