Question

Three elements A, B,and C have 3,4 and 2 electrons respectively in their outermost shell. Give the group number to which they belong in the modern periodic table. Also, give their valencies

Answer 1

valency of group A is 3,valency of B is 4,valency of C is 2 respectively. they all are not present in same group because the no of electrons present in last shell or valence electrons are same of all elements down the group.

Answer 2

Hii dear,

# Valency-
It's the tendency of the atom to gain or lose free electrons.

◆ Answer-
(A) For element A -
Electrons in outermost shell = 3
Group number = Gr. 13
Valency = +3

(B) For element B -
Electrons in outermost shell = 4
Group number = Gr. 14
Valency = +4, -4

(C) For element C -
Electrons in outermost shell = 2
Group number = Gr. 2
Valency = +2

Hope this helps...