Question

Statement I: Two atoms of X combine with three atoms of Y to form ${\text{X}}_2{\text{Y}}_3$.

Statement II: From the chemical formula of the compound ${\text{X}}_2{\text{Y}}_3$, we can conclude that the valency of X is 2.

• A. Statement I is true but II is false
• B. Statement I is false but II is true
• C. Both statements I and II are true
• D. Both statements I and II are false.

Answer 1

The correct option is A Statement I is true but II is false

A chemical formula is a symbolic representation that indicates the number of atoms present in the molecule.

$\bullet$ From the chemical formula ${\text{X}}_2{\text{Y}}_3$, we can understand that two atoms of X combine with three atoms of Y to form one molecule of ${\text{X}}_2{\text{Y}}_3$.

$\bullet$ We obtain the chemical formula by cross multiplication of valencies.
Symbol: X Y
$\searrow \swarrow$ Valency: 3 2

Hence, the valency of Y is 2 and that of X is 3.