1

### IIT-JEE 1985

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

Solve by yourself
2

### IIT-JEE 1984

Subjective
The electron energy in hydrogen atom is given by E = (-21.7 $\times$ 10-12)/n2 ergs. Calculate the energy required to remove an electron completely from the n = 2 orbit. What is the longest wavelength (in cm) of light that can be used to cause this transition?

5.42 $\times$ 10-12 ergs, 3.67 $\times$ 10-5 cm
3

### IIT-JEE 1982

Subjective
Calculate the wavelength in Angstrom of the photon that is emitted when an electron in the Bohr orbit, n = 2 returns to the orbit, n = 1 in the hydrogen atom. The ionization potential of the ground state hydrogen atom is 2.17 $\times$ 10-11 erg per atom.

1220 Å
4

### IIT-JEE 1981

Subjective
The energy of the electron in the second and the third Bohr's orbits of the hydrogen atom is -5.42 $\times$ 10-12 erg and -2.41 $\times$ 10-12 erg respectively. Calculate the wavelength of the emitted radiation when the electron drops from the third to second orbit.

6.603 Å