Reason
Its degree of dissociation is high.
Assertion
$$D_2O$$ is called hard water.
A
Both Assertion and Reason are incorrect
B
Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
C
Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
D
Assertion is correct but Reason is incorrect
Correct option is D. Both Assertion and Reason are incorrect
Correct assertion: $$D_2O$$ is called heavy water.
Correct reason: Due to stronger D-O bonds, the degree of dissociation of $$D_2O$$ is lower than that of $$H_2O$$.
Hence, Option "D" is the correct answer.