Question

Assertion :Among the second group peroxides, barium peroxide is thermally most stable. Reason: Positive charge density is maximum for $B{a}^{2+}$ among group II cations

• A. The Assertion is True, Reason is True; Reason is a correct explanation for Assertion
• B. The Assertion is True, Reason is True; Reason is not a correct explanation for Assertion
• C. Assertion is True, Reason is False.
• D. Assertion is False, Reason is True.

Answer 1

The correct option is C Assertion is True, Reason is False.

Charge density: As the size of atom increases (with the same charge) the charge density (charge/size) decreases, as $B{a}^{2+}$ has the highest size among the group so it's charge density is least.
The stability of the peroxides increases as the size of the metal increases so $B{a}^{2+}$ forms most stable peroxide.