Question

How many molecules of H2O are there in 1.0 g of H2O?

Answer 1

the molar mass of H2O=18
no. of moles = mass/molar mass =1/18 mole
no. of molecules = no. of moles*avogadro's number
avogaro's number= 6.022*10^23
so
no. of molecules =1/18 *6.022*10^23