Which statement is incorrect?
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → Reactions in which energy is absorbed are known as Exothermic Reactions.
Reactions that give out heat are exothermic; reactions that absorb energy are endothermic. So statement (3) gives the wrong name, which makes it the incorrect statement.
The other three statements are correct:
Option (1) — a precipitation reaction gives an insoluble salt that settles out as a precipitate, e.g. barium sulphate from barium chloride and sodium sulphate.
Option (2) — gain of oxygen (or loss of hydrogen) by a substance is oxidation.
Option (4) — gain of hydrogen (or loss of oxygen) by a substance is reduction.