CBSE Class 10 Science 2020 · Paper 31/2/1 · Question 17

Periodic Classification of Elements 3 marks Medium

From the elements

_{19}^{39} A

_{14}^{28} B

_{8}^{16} C

and

_{18}^{40} D

identify :

(a)the most electro positive element.
(b)a noble gas.
(c)a metalloid.
(d)an element which will gain 2 electrons to attain nearest noble gas configuration.
(e)formula of compound formed between A and C.
(f)elements belonging to same period.

Answer

A is most electropositive, D a noble gas, B a metalloid, C gains 2 electrons; formula $A_{2} C$ ; B and D in period 3.

(a) A (configuration

2, 8, 8, 1

): it loses its single valence electron most easily. (b) D (

2, 8, 8

): its outer shell is full. (c) B (

2, 8, 4

): silicon, a metalloid. (d) C (

2, 6

): it gains

2

electrons to reach

2, 8

, the configuration of neon. (e)

A_{2} C

(A has valency

1

, C has valency

2

). (f) B and D: both have three shells, so both are in period 3.

🔒 Step-by-step solution