Question

मोल सिद्धांत क्या है? 45g पानी में अणुओं की संख्या की गणना कीजिये

Answer 1

Sorry I could not answer in Hindi.
I am giving English translation of question.
What is mole?
Calculate the number of molecules present in 45g of water molecule.

Mole:
A Mole of a substance is the amount of substance which contains 6.022 × 10 ^23 particles ( atoms,molecules or ions) of substance.
Molecular weight of water: H2O
= 2x1+16
=18unified mass
Molar mass of H2O= 18g
1 mole --18g contains 6.022x10^23 molecules.
45g of water contains ------?
= 45x6.022x10^23/18
=2.5 x 6.022x10^23
=15.055 ×10^23 molecules

Therefore 45g of H2O contains 15.055 x10^23 molecules.