question_answer 111)

    Assertion (A) The highest oxidation state of osmium is +8. Reason (R) Osmium is a 5d-block element.

Answer:

                    (b) Assertion and reason both are correct but reason is not the correct explanation of assertion.                                                        . The highest oxidation state of osmium is +8 due to its ability to expand their octet by using its all 8 electrons (2 from 6s and 6 from 5d).