The statement below is followed by four options. Each option is related to the item in the statement, but only one is always true. Select the option that always holds and makes the statement true.
"A compound always has ______."
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → Two or more elements
The answer must hold for every compound, without exception. An option that is present in most cases but can be missing in even one case is not always true.
Option (1) Two or more elements — a compound is formed when two or more elements combine chemically in a fixed proportion, so this is always true.
Option (2) Oxygen — sodium chloride (common salt) has no oxygen.
Option (3) A metal — water and carbon dioxide contain no metal.
Option (4) A liquid state — common salt is a solid and carbon dioxide is a gas.