Past Year - 3 Mark Questions

Class 10
Chapter 5 Class 10 - Periodic Classification of Elements

## (c) Name the element ‘X’ and state whether it is metallic or non-metallic.

X belongs to the 3rd period. So, it has 3 shells.

X belongs to the 16th group.

Group number = 10 + number of valence electrons

16 = 10 + number of valence electrons

Number of valence electrons = 16 - 10 = 6

Valency = 8 - 6 = 2

(a)

Number of valence electrons of X = 16 - 10 = 6

Valency of X = 8 - 6 = 2

(b)

X has a valency of 2 and Hydrogen has a valency of 1 so the formula of the compound formed by them will be H 2 X

Electron dot structure of H 2 X:

(c)

The element X is sulphur.

Metals lose electrons to become stable whereas, non-metals gain electrons to become stable.

Sulphur gains electrons to become stable. Hence it is a non-metal.

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#### Maninder Singh

CA Maninder Singh is a Chartered Accountant for the past 13 years and a teacher from the past 17 years. He teaches Science, Economics, Accounting and English at Teachoo