Question

Assertion (A) : Actinoids show wide range of oxidation states.
Reason (R) : This is due to comparable energies of 5f, 6d and 7s orbitals.

• A. Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).
• B. Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).
• C. Assertion (A) is true, but Reason (R) is false.
• D. Assertion (A) is false, but Reason (R) is true.

Hint:

Actinoids have 5f, 6d and 7s orbitals of comparable energy, so many electrons can take part in bonding. R explains A.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
This is an assertion-reason question. We check whether A is true, whether R is true, and then whether R explains A.

Step 2: Check the Assertion (A).
Actinoids show many oxidation states. The common one is +3, but elements like U, Np and Pu show +4, +5, +6 and even +7. For example, uranium shows +3, +4, +5 and +6. So (A) is TRUE.

Step 3: Check the Reason (R).
In actinoids the 5f, 6d and 7s orbitals lie very close in energy. So electrons from all three sets can be used for bonding. This is a true fact, so (R) is TRUE.

Step 4: Does R explain A?
Because the three sets of orbitals have comparable energies, an actinoid atom can lose a different number of electrons in different compounds. That gives the wide range of oxidation states. So (R) is the correct explanation of (A).

Final Answer:
Both statements are true and R explains A, so the answer is option (A). \[ \boxed{\text{(A)}} \]