Question

Given below are two statements : 
Statement I : CrO\( _3 \) is a stronger oxidizing agent than MoO\( _3 \) 
Statement II : Cr(VI) is more stable than Mo(VI) In the light of the above statements, choose the correct answer from the options given below

• A. Statement I is false but Statement II is true
• B. Statement I is true but Statement II is false
• C. Both Statement I and Statement II are true
• D. Both Statement I and Statement II are false

Hint:

Remember the trends in oxidizing power and stability of oxidation states down a group in transition metals. For oxides in higher oxidation states, oxidizing power typically decreases down the group, while the stability of higher oxidation states often increases down the group for heavier elements.

Answer 1

The Correct Option is B

Statement I: CrO\( _3 \) is a stronger oxidizing agent than MoO\( _3 \) In the same group of transition metals, the oxidizing power of oxides in higher oxidation states generally decreases down the group. 
Chromium (Cr) and Molybdenum (Mo) belong to Group 6. CrO\( _3 \) has Cr in the +6 oxidation state (Cr(VI)), and MoO\( _3 \) has Mo in the +6 oxidation state (Mo(VI)). Due to the smaller size and higher electronegativity of Cr compared to Mo, Cr(VI) is more prone to reduction to lower oxidation states, making CrO\( _3 \) a stronger oxidizing agent than MoO\( _3 \). 
Therefore, Statement I is true. Statement II: Cr(VI) is more stable than Mo(VI) Down a group in transition metals, the stability of higher oxidation states generally decreases for the elements in the first row (like Cr) compared to the elements in the second and third rows (like Mo and W). 
This is due to the inert pair effect becoming less significant and the ability to form stable compounds in higher oxidation states increasing down the group for heavier elements. Consequently, Mo(VI) and W(VI) are generally more stable in their oxide forms (MoO\( _3 \), WO\( _3 \)) than Cr(VI) in CrO\( _3 \), which tends to be a strong oxidizing agent and readily reduced. 
Therefore, Statement II is false. In conclusion, Statement I is true, but Statement II is false. This corresponds to option (2).