CO2 is acidic in nature and KOH is a strong base. Hence, CO2 is absorbed by KOH solution and both react to form potassium carbonate and water.
Li is used in making electrochemical cells like Li-ion batteries, as it is lighter, cheaper , has high energy density & electrode potential.
Cs having very low ionisation enthalpy, easily emits electrons when exposed to sunlight. Hence it is widely used in photoelectric cells.
Liquid Na is used as a coolant in fast breeder reactors on account of its excellent heat transfer properties.
KOH→ Absorbs CO2
Li→ Used in Electro chemical cells
Na→ Coolant in fast breeder reactors
Cs→ Used in photoelectric cells