An atom forms an ion by losing three electrons. The ion has an electronic configuration [Ar]3d⁶. The symbol of the ion is :

1.	Fe3+	2.	Ni3+
3.	Co3+	4.	Mn+3

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 mass ratio of photons corresponding to the first lines of the Lymann and the Balmer series of the atomic spectrum of hydrogen is :

If the size of the first orbit of the hydrogen atom is 5.29 nm, the size of the second orbit of He⁺ is

1. 2.65 nm

2. 21.16 nm

3. 10.58 nm

4. 5.29 nm

The quantum number of the most energetic electron in an Ne atom in the first excited state is

The correct order of increasing energy of atomic orbital is: 

1. 3s, 3p, 4s, 3d, 4p

2. 3s, 3p, 3d, 4s, 4p

3. 3s, 3p, 4s, 4p, 3d

4. 3s, 3p, 3d, 4p, 4s

An absorption line of the lowest frequency in the transition of hydrogen spectra is:

1. n=1 to n=2

2. n=3 to n=8

3. n=2 to n=1

4. n=8 to n=3

Which of the following has greater number of electrons than neutrons?

1. Al³⁺

2. O^2-

3. F^-

4. C

The transition in the He⁺ ion in the balmer series that would have the same wave number as the first Lyman line in the hydrogen spectrum is-

The number of electrons in  ₁₉ K with quantum numbers n=3; l=0 is/are:

1. 2

2. 1

3. 4

4. 3