The basic difference between Mendeleev’s Periodic Law (A) and Modern Periodic Law (B) is:

1.	A is based on atomic weights while B is based on atomic numbers.
2.	B is based on atomic weights while A is based on atomic numbers.
3.	A is based on the number of isotopes while B is based on atomic numbers.
4.	A is based on physical properties while B is based on chemical properties.

The period and group number of the element with Z =114 are:

The ionic radius indicates the distance between the nucleus and:

1. Outermost shell of an atom.

2. Outermost shell of an ion.

3. Outermost shell of the cation only.

4. Outermost shell of the anion only.

 The trend of atomic radius in a period and a group is :

The energy of an electron in the ground state of the hydrogen atom is $–2.18\times {10}^{-18}J$.  The ionization enthalpy of atomic hydrogen in terms of J ${\mathrm{mol}}^{-1}$ is:

1. 2.81 × 10⁶ J mol${}^{-1}$

2. 1.31 × 10⁶ J mol${}^{-1}$

3. 2.31 × 10⁶ J mol${}^{-1}$

4. 1.81 × 10⁶ J mol${}^{-1}$

The first ionization enthalpy values (in kJ mol^–1) of group 13 elements are :

The explanation for the deviation from the general trend can be -

1. Ga has lower ionization enthalpy than Al.

2. Ga has higher ionization enthalpy than Al.

3. Al has higher ionization enthalpy than Ga. 

4. Ga has a lesser valence electron than Al.

An element with higher negative electron gain enthalpy in the given pair is:

(i) O or F  (ii) F or Cl
1. O, Cl
2. F, F
3. O, F
4. F, Cl  

The basic difference between the  electron gain enthalpy (E_a) and electronegativity (E_N) is:

The statement that "the electronegativity of N on the Pauling scale is 3.0 in all the nitrogen compounds" is incorrect because:

The correct statement about the radius of a species is :