Question

The atomic number of four elements A, B, C and D are 12, 13, 15 and 3 respectively. The element which cannot form a cation is (a) A
(b) B
(c) C
(d) D

Answer 1

Answer:

c

Explanation:

its electronic configuration is 2,8,5 means its valency is negative 3

Answer 2

Answer is Option (C)

Explanation:

Given Elements A, B, C, D have the atomic number as -

A = 12

B = 13

C = 15

D = 3

So the electronic configurations are -

• A = 12 Atomic Number = 2, 8, 2

It has 2 electrons in outermost shell, losing them to be cation.

• B = 13 Atomic Number = 2, 8 , 3

It has 3 electrons in outermost shell, losing them to be cation.

• C = 15 Atomic Number = 2, 8, 5

It has 5 electrons in outermost shell, gaining three more can make it anion.

• D = 3 Atomic Number = 2, 1

It has 2 electrons in outermost shell, losing it to be cation.

So, C is the one which cannot lose but gain electron, making itself an Anion.