Question

Two chemical species A and B combine to form C which contains both A and B. A and B cannot be broken down into simpler substances by simple chemical reactions.

$\mathrm{A}+\mathrm{B}\to \mathrm{C}$

Which of the following are correct?

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

Answer 1

The correct option is A

(i), (ii) and (iv)

Explanation for the correct option:

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

• It is given that, A and B cannot be broken down into simpler substances. Therefore A and B are elements as elements cannot be broken down into simpler substance.
• It is given that C contains both A and B which are chemically combined through a chemical reaction, therefore C is a compound.
• In a compound, elements combine in a fixed composition. So C has a fixed composition.

Explanation for the incorrect options:

(B) (i), (ii) and (iii): (i) and (ii) are correct but (ii) is incorrect as A and B are elements instead of a compound.

• It is because elements can not be broken down into simpler substances whereas compounds can be broken into simpler substances using chemical methods.

(C) (i), (iii) and (iv): (i) and (iv) are correct but (iii) is incorrect.

• It is because elements can not be broken down into simpler substances whereas compounds can be broken into simpler substances using chemical methods.

(D) (ii), (iii) and (iv): (ii) and (iv) are correct but (iii) is incorrect.

• It is because elements can not be broken down into simpler substances whereas compounds can be broken into simpler substances using chemical methods.

Hence, option (A) is correct.