In the following reaction sequence the major products A and B are :

The increasing order of the acidity of the $$\alpha $$-hydrogen of the following compounds is :

Which of the following derivatives of alcohols is unstable in an aqueous base?

The difference between the radii of 3^rd and 4^th
orbits of Li²⁺ is R₁ . The difference between the
radii of 3^rd and 4^th orbits of He⁺ is $$\Delta $$R₂ .
Ratio $$\Delta $$R₁ : $$\Delta $$R₂ is :