Question

In 90 gram of water
a) How many molecules are present in it?
b) What will be the total number of atoms ?
c) Find the volume of same amount of water vapour at STP ( Atomic mass of hydrogen and oxygen are 1 & 16)​

Answer 1

Answer:

a] To determine the number of molecules in a particular compound, we need to first determine the number of moles present in that mass.

18 g of H2O =1 mole

1 g of H2O=(1÷18) moles

90 g of H2O= (1÷18)×90 moles=5 mol

Now, as we know,

1 mole=6.022×10^(23) molecules

therefore 5 moles= 5×6.022×10^(23)=30.11 ×10^(23) molecules

Hence 90 g of water will contain 30.11×10^(23) molecule..

Explanation: