Question

water being separated with an electric current into hydrogen and oxygen gas best illustrates that
a water is a mixture.
b. water is a compound.
c. water is an element.
d. water is a conductor.
e. water is an isotope.

Explanation:

• Option A: A mixture is a combination of substances that retain their properties. Water is not a mixture (it has a fixed composition of H₂O), so A is incorrect.
• Option B: A compound is a substance made of two or more different elements chemically bonded. Water (H₂O) can be decomposed into H₂ and O₂ (different elements), showing it's a compound. This matches the decomposition by electric current (electrolysis of water).
• Option C: An element is a pure substance with only one type of atom. Water has two types (H and O), so C is wrong.
• Option D: While water is a conductor, the decomposition into H and O shows its chemical nature (being a compound) more directly than its conductivity. So D is not the best fit.
• Option E: Isotopes are variants of an element with different neutrons. Water is a compound, not an isotope, so E is wrong.

Answer:

B. water is a compound.