Question

Which of the given elements A, B, C, D and E with atomic number 2, 3, 7, 10 and 30 respectively belong to the same period?

पर्याय

• A, B, C

• B, C, D

• A, D, E

• A, D, E

Answer 1

B, C, D

Explanation -

Electronic configuration of A = 2

Electronic configuration of B = 2,1

Electronic configuration of C = 2,5

Electronic configuration of D = 2,8

Electronic configuration of E = 2,8,8,8,4

If the electronic configuration of the given elements is written, only elements B, C and D have electrons occupying only two shells. So, only elements B, C and D would be placed in the same period in the modern periodic table.