Question

Two substances, A and B were made to react to form a third substance, ${\mathrm{A}}_2\mathrm{B}$ according to the following reaction $2\mathrm{A}+\mathrm{B}\to {\mathrm{A}}_2\mathrm{B}$ which of the following statements concerning this reaction are incorrect? (i) The product ${\mathrm{A}}_2\mathrm{B}$ shows the properties of substances A and B (ii) The product will always have a fixed composition (iii) The product so formed cannot be classified as a compound (iv) The product so formed is an element.

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

Answer 1

The correct option is C

(i), (iii) and (iv)

The explanation for the correct option

(C) (i), (iii) and (iv)

Chemical reaction

• Chemical reactions, in which reactants combine to form products, are represented by chemical equations.
• Stoichiometric coefficients are added to the reactants and products to balance chemical equations.
• It's significant because the principles of mass conservation and constant proportions require a chemical equation to be applied.
• When the law of conservation of mass is applied to a chemical, neither an atom is generated nor destroyed on either side of the reaction, resulting in an equal number of elements in both the reactant and the product.

Two substances react to form a third substance

• The given reaction is as follows:

$2\mathrm{A}+\mathrm{B}\to {\mathrm{A}}_2\mathrm{B}$

• ${\mathrm{A}}_2\mathrm{B}$ is a compound.
• ${\mathrm{A}}_2\mathrm{B}$ is a compound composed of two elements $\mathrm{A}$ and $\mathrm{B}$.
• The properties of a compound ${\mathrm{A}}_2\mathrm{B}$ differ significantly from those of its element constituents $\mathrm{A}$ and $\mathrm{B}$.
• The composition of a compound ${\mathrm{A}}_2\mathrm{B}$ is fixed.

The explanation for incorrect options

• The product's composition is always fixed.
• Hence, all the other options (A), (B) and (D) are incorrect.

Therefore, the correct option is (C) (i), (iii) and (iv).