Number of electrons in the valence orbit of nitrogen in an ammonia molecule is

• 8

• 5

• 6

• 7

The product obtained on fusion of BaSO₄ and Na₂CO₃ is

• BaCO₃

• BaO

• Ba(OH)₂

• BaHSO₄

The electronic configuration of elements A, B and C are [He] 2s¹, [Ne] 3s¹ and [Ar] 4s¹ respectively, which one of the following order is correct for the first ionization potentials (in kJ mol^-1) of A , B and C?

• A > B > C

• C > B > A

• B > C > A

• C > A > B

Coordination number of aluminium is

• 8

• 12

• 6

• 4

Ionic radius (in Å) of As³⁺, Sb³⁺ and Bi³⁺ follow the order

• As³⁺ > Sb³⁺ > Bi³⁺

• Sb³⁺ > Bi³⁺ > As³⁺ 

• Bi³⁺ > As³⁺ > Sb³⁺

• Bi³⁺ > Sb³⁺ > As³⁺

Let electronegativity, ionisation energy and electron affinity be represented as EN, IP and EA respectively. Which one of the following equation is correct according to Mulliken?

• EN = IP × EA

• EN = $\frac{\mathrm{IP}}{\mathrm{EA}}$

• $\mathrm{EN}\hspace{0.17em}= \frac{\mathrm{IP}\hspace{0.17em}+ \mathrm{EA}}{2}$

• EN = IP - EA

The element with atomic number 12 belongs to .... group and .... period

• I A, third

• III A, third

• II A, third

• II A, second

Which one of the following represents the correct order of electronegativity ?

• P > O > N

• N > P > O

• O > N > P

• N > O > P

79.

Which one of the following is not an iso-electronic pair?

• Mg²⁺, C^4-

• N^3-, O^2-

• N^2-, O^2-

• F^-, Al³⁺

Which of the following pairs of ions are colourless ?

• Ti³⁺, Cu²⁺

• Sc³⁺, Zn²⁺

• Co²⁺, Fe³⁺

• Ni²⁺, V³⁺