Question

Two atoms of $\text{X}$ react with two atoms of $\text{Y}$ to form ______ molecules of $\text{XY}$.

• A. four
• B. eight
• C. two
• D. six

Answer 1

The correct option is C two

Writing the word equation in the form of symbols, we get
$2\text{X}+2\text{Y}\to \text{\_\_\_XY}$
For an element, the number of atoms in the reactants should be equal to the number of atoms in the products (Law of conservation of mass)
Here,
Number of atoms of $\text{X}$ in reactants = $2$
Number of atoms of $\text{Y}$ in reactants = $2$
Number of atoms of $\text{X}$ in products = $1$
Number of atoms of $\text{Y}$ in products = $1$
To balance the number of $\text{X}$ and $\text{Y}$ atoms, we need to multiply $\text{XY}$ by $2$.
$2\text{X}+2\text{Y}\to \text{\_\_\_XY}$
Therefore, the number of molecules of $\text{XY}$ in the products will be $2$.