The INCORRECT statement(s) about heavy water is (are)
(A) used as a moderator in nuclear reactor
(B) obtained as a by-product in fertilizer industry
(C) used for the study of reaction mechanism
(D) has a higher dielectric constant than water
Choose the correct answer from the options given below :

Solution

Chemistry ma’am · 2 steps

D₂O is almost a copy of water, but its dielectric constant is slightly lower, so only (D) is false.

1. What heavy water is. Heavy water is D₂O, water made with deuterium in place of ordinary hydrogen. Its chemistry is close to that of H₂O, but the heavier isotope changes its physical constants slightly.

   Statement	Correct?	Reason
   (A) moderator in nuclear reactors	Yes	D₂O slows down fast neutrons but captures very few of them
   (B) by-product of the fertilizer industry	Yes	It is made by exhaustive electrolysis of water, or obtained as a by-product in some fertilizer industries
   (C) used to study reaction mechanisms	Yes	Deuterium works as a tracer, so you can follow where the H atoms go in a reaction
   (D) higher dielectric constant than water	No	78.06 for D₂O against 78.39 for H₂O at 298 K, so it is lower

2. So. Statements (A), (B) and (C) are all correct. The only incorrect statement is (D), so the answer is option (a).

The idea to keep. Learn the main uses of D₂O: moderator, tracer, and a by-product of fertilizer plants. Among its constants, only density, melting point, boiling point and viscosity are higher. The dielectric constant is lower.

Answer from the NTA final answer key. Solution by PrepWiser.