Question

how many molecule of water are there in 1 litre of water

Answer 1

The liter of water has 1000 grams. The number of moles is 1000/18 = 55.556 moles. The number of molecules is therefore 6.022*1023 *55.556 = 3.346*1025 molecules. The number of atoms is 3 times larger because each molecule has three atoms, so there are 1.0038*1026 atoms in a liter of water . hope it helps you

Answer 2

Since the density of water= 1g/ml or 1000g / 1000ml = 1000g / 1L
So the mass of 1 L of water = 1000g 
No. of moles = given mass / molecular mass of water 
= 1000g / 18g
​= 55.56 moles molecule of water
1 mole = 6.023 x 1023 molecules
55.56 moles = 55.56 x 6.023 x 1023 molecules​ 
= 3.34 x 1025 molecules of water in 1Lwater


Thank you