221.

The ground state term symbol for an electronic state is governed by :

• Heisenberg's principle

• Hund's rule

• Aufbau principle

• Pauli exclusion principle

What is the ratio of mass of an electron to the mass of a proton ?

• 1 : 2

• 1 : 1

• 1 : 1837

• 1 : 3

The number of orbitals present in the shell with n = 4 is:

• 16

• 8

• 18

• 32

The correct set of quantum number for the unpaired electrons of chlorine atoms is

• 2, 1, -1, +1/2

• 2, 0, 0,+ 1/2

• 3, 1, 1, ±1/2

• 3, 0, 0, ±1/2

The number of electrons in the valence shell of sulphur in SF₆ is :

• 12

• 10

• 8

• 11

Rutherford's experiment on the scattering of α-particles showed for the first time that the atom has:

• electrons

• protons

• nucleus

• neutrons

For a Bohr atom angular momentum M of the electron is : (n = 0, 1, 2......)

• $\frac{{\mathrm{nh}}^2}{4\mathrm{\pi }}$

• $\frac{{\mathrm{n}}^2{\mathrm{h}}^2}{4\mathrm{\pi }}$

• $\frac{\sqrt{{\mathrm{nh}}^2}}{4\mathrm{\pi }}$

• $\frac{\mathrm{nh}}{2\mathrm{\pi }}$

The radius of hydrogen atom in the ground state is 0.53 Å. The radius of Li²⁺ ion (atomic number = 3) in a similar state is :

• 0.176 Å

• 0.30 Å

• 0.53 Å

• 1.23 Å

The wavelength of the radiation emitted, when in a hydrogen atom electron falls from infinity to stationary state 1, would be (Rydberg constant = 1.097 × 10⁷ m^-1)

• 91 nm

• 192 nm

• 406 nm

• 9.1 × 10^-8 nm

The radioactive isotope ${}_{27}{}^{60}\mathrm{Co}$ which is used in the treatment of cancer can be made by (n, p) reaction. For this reaction the target nucleus is

• ${}_{28}{}^{59}\mathrm{Ni}$

• ${}_{27}{}^{59}\mathrm{Co}$

• ${}_{28}{}^{60}\mathrm{Ni}$

• ${}_{27}{}^{60}\mathrm{Co}$