Among the following which one has the highest cation to anion size ratio ?

Among the elements Ca, Mg, P and Cl, the order of increasing atomic radii is

In which of the following molecules the central atom does not have sp³ hybridization?

Some of the properties of the two species, $$NO_3^ - $$ and $${H_3}{O^ + }$$ are described below. Which one of them is current?