If the electronic structure of oxygen atom is written as $1{\mathrm{s}}^2, 2{\mathrm{s}}^2$  it would violate:

1. Hund's rule.

2. Paulis exclusion principle.

3. Both Hund's and Pauli's principles.

4. None of the above.

The ratio of the wavelengths of the last lines of the Balmer to Lyman series is

The mass and charge of one mole of electrons are, respectively:

1. 5.48 × ${10}^{-7}$ kg, 9.65 C, 
2. 5.48 × ${10}^{-7}$ C, 1.098 x 10²⁷
3. 5.48 × ${10}^{-7}$ kg, 9.65 × ${10}^4$ C
4. 9.65 × ${10}^4$ C, 1.098 x 10²⁷

The maximum number of neutrons are present in the nuclei of

$1.$ ${\mathrm{O}}_8^{16}$
$2.$ ${\mathrm{Mg}}_{12}^{24}$
$3.$ ${\mathrm{Fe}}_{26}^{56}$
$4.$ ${\mathrm{Sr}}_{38}^{88}$

The complete symbol for the atom with the given atomic number (Z) and atomic mass (A) would be, respectively,

1.  ${}_4{}^9\mathrm{Be}$   ${}_{92}{}^{233}\mathrm{U}$     ${}_4{}^9\mathrm{Be}$

2.  ${}_{17}{}^{35}\mathrm{Cl}$    ${}_{92}{}^{233}\mathrm{U}$    ${}_4{}^9\mathrm{Be}$

3.  ${}_4{}^9\mathrm{Be}$    ${}_{17}{}^{35}\mathrm{Cl}$     ${}_{92}{}^{233}\mathrm{U}$

4. ${}_{92}{}^{233}\mathrm{U}$    ${}_4{}^9\mathrm{Be}$    ${}_{17}{}^{35}\mathrm{Cl}$