Question

Which of the following statements are correct regarding the general characteristics of IIIA group elements?
i) The decreasing order of E.N. of IIIA group elements is $B>Tl>In>Ga>Al$.
ii) The S.R.P. values decreases in the order $Tl>In>Ga>B>Al$.
iii) Ga has high melting point because of its polymeric structure.

• A. i and ii
• B. ii and iii
• C. only ii is correct
• D. i and iii

Answer 1

The correct option is A i and ii

Electronegativity should decrease along with the group but in the case of boron family as we move from B to Al, due to an increase in atomic size and hence nuclear charge on electrons decreases and hence electronegativity.

From Al to Tl, size increases but effective nuclear charge increases due to poor shielding effect of inner d and f orbitals and hence the electronegativity.

E.N values---

B - 2.0

Al - 1.5

Ga - 1.6

In - 1.7

Tl - 1.8

S.R.P values-

B - - 0.89

Al - -1.68

Ga - -0.56

In - +0.34

Tl- +0.72

Gallium has low melting point i.e. 303 K

Hence, option $A$ is correct.