Question

clalculate the molarity of pure water (density =1)

Answer 1

mol water / L water = 55.3/ 1 = 55.3 M

Answer 2

Density = 1 g/cm^3
Molarity =>
number of moles of solute/ volume of solution

Before finding the molarity letters find out the mass of the 1 litre of water.
Mass of 1 litre= density of water× Volume
M= 1×1 = 1 kg= 1000 g

Mass= mass of 1 kg of water/ molar mass
18= 1000\ M
M = 55.56 /litre