81.

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

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⁺

Which of the following is a favourable factor for cation formation?

• High electronegativity

• High electron affinity

• Low ionisation potential

• Smaller atomic size

Which of the following is correct?

• The number of electrons present in the valence shell of S in SF₆ is 12.

• The rates of ionic reactions are very slow

• According to VSEPR theory, SnCl₂ is a linear molecule.

• The correct order of ability to form ionic compounds among Na⁺, Mg²⁺ and Al³⁺ is  Al³⁺ >Mg²⁺ >Na⁺.

Observe the following statements :

I. The physical and chemical properties of elements are periodic functions of their electronic configuration.

II. Electronegativity of fluorine is less than the electronegativity of chlorine.

III. Electropositive nature decreases from top to bottom in a group.

The correct answer is :

• I, II and III are correct

• only I is correct

• only I and II is correct

• only II and III are correct