Question

Pairs of elements and their valencies are given in the following table. Use them logically to deduce the molecular formulae of the compounds formed from the pairs and write them in the last column.
Element Valency Molecular formula of the corresponding compound
C 4
H 1

N 3
H 1

Fe 2
S 2

C 4
O 2

Answer 1

1-CH4
2-NH3
3-FeS
4-CO2

Answer 2

Answer:

$CH_{4}$ , $NH_{3}$ ,$FeS$ and  $CO_{2}$.

Explanation:

Since we know that valency is defined as the combining capacity of an element.

(a)carbon has a valency of 4 and hydrogen has a valency of 1. So, resultant compound is methane $CH_{4}$

(b)Nitrogen has a valency of 3 and hydrogen has a valency of 1. So, resultant compound is ammonia $NH_{3}$

(c)Iron has a valency of 2 and sulphur has a valency of 2. So, resultant compound is ironsulphide $FeS$

(d)Carbon has a valency of 4 and oxygen has a valency of 2. So, resultant compound is Carbon di-oxide $CO_{2}$.