Question

Which of the following statements are NOT correct?
A. Hydrogen is used to reduce heavy metal oxides to metals. 
B. Heavy water is used to study reaction mechanism. 
C. Hydrogen is used to make saturated fats from oils.
D. The H-H bond dissociation enthalpy is lowest as compared to a single bond between two atoms of any element. 
E. Hydrogen reduces oxides of metals that are more active than iron. 
Choose the most appropriate answer from the options given below :

• A. B, D only
• B. D, E only
• C. A, B, C only
• D. B, C, D, E only

Answer 1

The Correct Option is B

To determine which statements are incorrect, let's analyze each statement:

• A. Hydrogen is used to reduce heavy metal oxides to metals.
  • This statement is generally correct. Hydrogen is often used as a reducing agent in metallurgical processes to reduce metal oxides like CuO to Cu.
• B. Heavy water is used to study reaction mechanisms.
  • This is also correct. Heavy water (D₂O) is employed in kinetic isotope effects to study reaction mechanisms due to the isotopic differences compared to regular water.
• C. Hydrogen is used to make saturated fats from oils.
  • This statement is correct. Hydrogenation is the process by which oils are converted into saturated fats by adding hydrogen.
• D. The H-H bond dissociation enthalpy is lowest as compared to a single bond between two atoms of any element.
  • This statement is incorrect. The H-H bond has a high bond dissociation enthalpy, higher than many other single bonds like C-C or N-N, due to the strong attraction between the two hydrogen atoms.
• E. Hydrogen reduces oxides of metals that are more active than iron.
  • This statement is incorrect. Generally, more active metals than hydrogen in the reactivity series cannot be reduced by hydrogen gas.

Therefore, the incorrect statements are D and E. The correct answer is D, E only.