Question

Which of the following statements are true for pure substances?

(i) Pure substances contain only one kind of particle.

(ii) Pure substances may be compound or mixtures.

(iii) Pure substances have the same composition throughout.

(iv) Pure substances can be exemplified by all elements other than nickel.

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

Answer 1

The correct option is B

(i) and (iii)

The correct option is B.

Explanation of correct option:

Statement (i):

1. The substances, which are formed of only one kind of particle and possess a constant or fixed composition are known as pure substances.
2. Examples of pure substances are gold, diamond, copper, etc.
3. A pure substance is formed of only one kind of particle, which can be either molecules or atoms or elements or compounds.

Statement (iii):

1. The composition of a pure substance is similar throughout, that is, it is homogenous throughout.

Explanation of incorrect options:

Statement (ii):

1. A pure substance cannot be further separated into other types of matter by any physical procedure, however, a mixture can be separated as they are impure components, which comprise more than one particle, for example, salt solutions.
2. Pure substances can be further differentiated into compounds or elements.

Statement (iv):

1. Pure substances cannot be typified by all the elements other than a nickel as pure nickel is an element comprising only one kind of particle.
2. A pure substance generally takes part in a chemical reaction to produce predictable products.

Final answer: The correct statements are (i) and (iii).