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 mixture.
(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)

Characteristics of pure substance:-

• A pure substance contains only one type of particles which can either be atoms or molecules or elements or compounds.
• A pure substance cannot be separated into other kinds of matter by any physical process but a mixture can as they are impure substances because they contain more than one particles. Ex: salt solutions.
• A pure substance has fixed composition as well as fixed melting and boiling points. Ex: salt.
• Pure substances cannot be exemplified by all elements other than nickel because pure nickel is an element containing only one kind of particles.
  

Hence, the correct ans is (1) and (3).