Question

Statements about heavy water are given below A. Heavy water is used in exchange reactions for the study of reaction mechanisms B. Heavy water is prepared by exhaustive electrolysis of water C. Heavy water has higher boiling point than ordinary water D. Viscosity of $H _{2} O$ is greater than $D _{2} O$

• A. $A , B$ and $C$ only
• B. $A $ and $B$ only
• C. $A$ and $D$ only
• D. $A$ and $C$ only

Answer 1

The Correct Option is A

Let's analyze each statement about heavy water to determine their accuracy:

1. Statement A: Heavy water is used in exchange reactions for the study of reaction mechanisms.
   • Heavy water ($D_2O$) is indeed used in various chemical reactions to trace mechanisms. In these reactions, deuterium (a stable isotope of hydrogen found in heavy water) exchanges with hydrogen and helps in understanding reaction pathways.
   • This statement is true.
2. Statement B: Heavy water is prepared by exhaustive electrolysis of water.
   • Heavy water is often produced through prolonged electrolysis of ordinary water ($H_2O$), where lighter hydrogen atoms are preferentially decomposed, leaving behind deuterium-enriched water.
   • This statement is true.
3. Statement C: Heavy water has a higher boiling point than ordinary water.
   • Heavy water has a boiling point of approximately 101.4°C, while ordinary water boils at 100°C at standard atmospheric pressure.
   • This statement is true.
4. Statement D: Viscosity of $H_2O$ is greater than $D_2O$.
   • The viscosity of heavy water ($D_2O$) is actually higher than that of regular water ($H_2O$), due to the greater mass of deuterium compared to hydrogen.
   • This statement is false.

Based on the analysis above, statements A, B, and C are correct. Therefore, the correct answer is:

$A , B$ and $C$ only

This understanding is crucial for recognizing the properties and preparation methods of isotopic compounds, which commonly appear in chemistry exams.