(a) Select a pair of isobars from the above table. (b) What would be the valency of element ‘B’ listed in the above table?

Question

In the following table, the mass number and the atomic number of certain elements are given:

Elements	A	B	C	D	E
Mass no.	1	7	14	40	40
Atomic no.	1	3	7	18	20

(a) Select a pair of isobars from the above table. 

(b) What would be the valency of element ‘B’ listed in the above table?

Answer 1

a. Elements D and E are isobars as they have a same mass number but a different atomic number. 

b. The atomic number of element B is 3. So, its electronic configuration is 2, 1. Hence its valency is 1 as it has only 1 valence electron.