1

### IIT-JEE 1993

Subjective
Estimate the difference in energy between 1st and 2nd Bohr orbit for a hydrogen atom. At what minimum atomic number, a transition from n = 2 to n = 1 energy level would result in the emission of X-rays with $\lambda = 3.0 \times {10^{ - 8}}$? Which hydrogen atom like species does this atomic number correspond to?

10.22 eV, 2, He+
2

### IIT-JEE 1990

Subjective
According to Bohr's theory, the electronic energy of hydrogen atom in the nth Bohr's orbit is given by ${E_n} = {{ - 21.6 \times {{10}^{ - 19}}} \over {{n^2}}}J$. Calculate the longest wavelength of light that will be needed to remove an electron from the third Bohr orbit of the He+ ion.

2055 Å
3

### IIT-JEE 1985

Subjective
What is the maximum number of electrons that may be present in all atomic orbitals with principal quantum number 3 and azimuthal quantum number 2?

10
4

### IIT-JEE 1985

Subjective
Give reasons why the ground state outermost electronic configuration of silicon is:

Solve by yourself