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

Answer: (B)

D, E only

Answer 2

A. Hydrogen is used to reduce heavy metal oxides to metals. - This statement is correct. Hydrogen gas is often used as a reducing agent in metallurgical processes to convert metal oxides to their respective metals.
B. Heavy water is used to study reaction mechanisms. - This statement is incorrect. Heavy water (D2O) is used to study the effects of isotopic substitution but is not typically used to study reaction mechanisms.
C. Hydrogen is used to make saturated fats from oils. - This statement is incorrect. Hydrogenation of oils involves the addition of hydrogen to unsaturated fats to produce saturated fats. However, a catalyst (such as nickel or platinum) is typically used in this process, not hydrogen gas itself.
D.The H-H bond dissociation enthalpy is lowest as compared to a single bond between two atoms of any element. - This statement is correct. The H-H bond dissociation enthalpy is the lowest among the diatomic molecules.
E. Hydrogen reduces oxides of metals that are more active than iron. - This statement is incorrect. Hydrogen gas is not commonly used to reduce metal oxides that are more active than iron. Other reducing agents, such as carbon or carbon monoxide, are typically used for this purpose.

Therefore, the incorrect statements are B and E, making option (B) D, E only the correct answer.