Question

Two substances X and Y react to form a new substance according to the following equation:

$2\mathrm{X}+\mathrm{Y}\to {\mathrm{X}}_2\mathrm{Y}$

Which of the following are incorrect?

• A. (i), (ii) and (iii)
• B. (i), (ii) and (iv)
• C. (i), (iii) and (iv)
• D. (ii), (iii) and (iv)

Answer 1

The correct option is B

(i), (ii) and (iv)

Explanation of correct option:

(B) (i), (ii) and (iv):

• Option (i) i.e. the product formed is an element is incorrect as the product ${\mathrm{X}}_2\mathrm{Y}$ is a compound. $\mathrm{X}$ and $\mathrm{Y}$ are combining chemically in a fixed ratio where 2 atoms of $\mathrm{X}$ have combined with one atom of $\mathrm{Y}$. Also, ${\mathrm{X}}_2\mathrm{Y}$ can be broken down into elements i.e. $\mathrm{X}$ and $\mathrm{Y}$. So the product is not an element.
• Option (ii) i.e. the product cannot be classified as a compound is incorrect because it can be classified as a compound. X and Y have combined chemically in a fixed ratio as shown in the chemical reaction to form a compound. and can be broken down into simpler substances i.e. elements.
• Option (iv) i.e. ${\mathrm{X}}_2\mathrm{Y}$ exhibits the properties of both A and B is incorrect because, in a compound, the properties of a compound are entirely different from the properties of the elements combining to form a compound.

Compound: A compound is a pure substance in which elements combine chemically in a fixed composition to give a compound.

• They can be broken down into elements that make up the compound by using chemical or electrochemical methods.
• The properties of the compound are entirely different from the elements from which it is formed.
• Example: Water $\left({\mathrm{H}}_2\mathrm{O}\right)$ is a compound.

Explanation of incorrect options:

(A) (i), (ii), and (iii): Option (i) i.e. the product formed is an element, and option (ii) i.e.; the product cannot be classified as a compound are incorrect but option (iii) i.e.; the product will always have a fixed composition is incorrect as compounds always have a fixed composition.

(C) (i), (iii), and (iv): Option (i) i.e. the product formed is an element, and option (iv) i.e. ${\mathrm{X}}_2\mathrm{Y}$ exhibits the properties of both A and B are incorrect but option (iii) i.e.; the product will always have a fixed composition is correct.

(D) (ii), (iii), and (iv): Option (ii) i.e.; the product cannot be classified as a compound, and option (iv) i.e. ${\mathrm{X}}_2\mathrm{Y}$ exhibits the properties of both A and B are incorrect but option (iii) i.e.; the product will always have a fixed composition is correct.

Hence, option (B) is correct.