Question

Which of the following statements are correct with respect to chemical reactions?
(i) Chemical composition of original substance changes
(ii) Formation of new substances takes place
(iii) Original substances can be obtained back from the new substances

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

Answer 1

The correct option is A (i) and (ii)

Chemical reactions are usually characterised by a chemical change, and yield one or more new substances, which usually have properties and composition different from that of the original substances.
The chemical composition of the original substances changes, resulting in the formation of new substances. Chemical reactions are generally irreversible, the new substances cannot be converted back into the original substances. Hence, statement (i) and (ii) are correct.