'25 volume' hydrogen peroxide means

The radius of the $$\mathrm{2^{nd}}$$ orbit of $$\mathrm{Li^{2+}}$$ is $$x$$. The expected radius of the $$\mathrm{3^{rd}}$$ orbit of $$\mathrm{Be^{3+}}$$ is

Which of the following conformations will be the most stable?

Given below are two statements : one is labelled as Assertion A and the other is labelled as Reason R :

Assertion A : Acetal / Ketal is stable in basic medium.

Reason R : The high leaving tendency of alkoxide ion gives the stability to acetal/ketal in basic medium.

In the light of the above statements, choose the correct answer from the options given below :