Which alkali metal is most metallic in character?

Which of the following oxides is not expected to react with sodium hydroxide?

Hydroxide of which alkali metal is used in the manufacture of soft soap?

Assertion $(A)$: $K$,$Rb$,and $Cs$ form superoxides.
Reason $(R)$: The stability of the superoxides increases from $K$ to $Cs$ due to the decrease in lattice energy.
The correct answer is:

Assertion : $KOH$ is more soluble in water than $NaOH$.
Reason : $NaOH$ is a stronger base than $KOH$.

An ore of potassium is