Question

1. Ordinary water, when compared to heavy water used in nuclear reactor is:
(a) Several times lighter
(b) Marginally lighter
(c) Half as heavy
(d) As heavy because chemically both are the same
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Answer 1

Answer:

I think the answer is c.

Answer 2

Answer:

Like ordinary water—H20—each molecule of heavy water contains two hydrogen atoms and one oxygen atom. ... In ordinary water, each hydrogen atom has just a single proton in its nucleus. In heavy water, each hydrogen atom is indeed heavier, with a neutron as well as a proton in its nucleus.