Question

The ratio of atomic numbers of two elements A and B is 1 : 2. The number of electrons present in the valence shell (3rd) of A is equal to the difference in the number of electrons present in the other two shells. Steps involved in the calculation of ratio of number of electrons present in a penultimate shell to antepenultimate shell of B are given below. Arrange them in the correct sequence.
(a) Calculation of atomic number of B.
(b) Calculation of valence electrons present in A.
(c) Calculation of atomic number of A.
(d) Calculation of number of electrons present in the penultimate shell and antepenultimate shell of B.
(e) Writing electronic configuration of B.

• A. b c d a e
• B. b c a e d
• C. d e b c a
• D. d b a c e

Answer 1

Answer: (B)

b c a e d