Question

The formula of the compound is $A_2{B}_5$. The number of electrons in the outermost orbits of A and B respectively are:

• A. 6&3
• B. 5&6
• C. 5&2
• D. 2&3

Answer 1

The correct option is B 5&6

The given compound is A2B5.

That means by using the formula, C1xN1=C2xN2,

we get

Ax2=Bx5

But as the valency of A is 2,

N1=(8-valency)

(ie.N1=8-2=6)

So,it becomes Ax6=Bx5

A/5=B/6

Therefore the answer is $A=5$ and $B=6$

here N1 is the no. of valence electrons in A and N2 is the no. of valence electrons in B.