Question

question 4 of 10
how is hydrogen in heavy water different from hydrogen in normal water?
a. the hydrogen atoms in heavy water have a neutron in the nucleus,
doubling the mass.
b. the heavy water molecules contain 3 hydrogen atoms instead of
2.
c. the hydrogen in heavy water is radioactive.
d. the hydrogen atoms in heavy water have an extra proton in the
nucleus.

Explanation:

• Option A: Heavy water (\(D_2O\)) has deuterium (\(D\)) which is a hydrogen isotope with one neutron in the nucleus. Normal water (\(H_2O\)) has hydrogen (\(H\)) with no neutrons. The mass of deuterium is double that of normal hydrogen (since mass of neutron ≈ mass of proton).
• Option B: Both normal water (\(H_2O\)) and heavy water (\(D_2O\)) have 2 hydrogen - like atoms (either \(H\) or \(D\)) per molecule.
• Option C: Deuterium (the hydrogen in heavy water) is not radioactive. Tritium (another hydrogen isotope) is radioactive.
• Option D: The number of protons in hydrogen (including its isotopes) is always 1. The difference between isotopes is in the number of neutrons, not protons.

Answer:

A. The hydrogen atoms in heavy water have a neutron in the nucleus, doubling the mass.