Question

How is heavy water different from normal water

Answer 1

The answer is C. An oxygen atom in heavy water has an extra neutron.

I say this because heavy water is also water, but it contains a higher proportion of the hydrogen isotope – deuterium. Two hydrogen atoms and one oxygen atom makes a water molecule. Deuterium is very much the same as that of normal hydrogen, but contains an extra neutron.

So therefore, the answer is C.

Answer 2

It's
$c)$
normal water has only one proton while heavy water (deuterium oxide) has a proton and a neutron