Question

the number of molecules in 100ml of 0.02N H2SO4?

Answer 1

H2SO4 → SO42- + 2H+
Since one mole of H2SO4 = 2 moles equivalents of H+
Therefore, molarity = normality/2
                                    = 0.01 M  
Now, 0.01M = 0.01=no. of moles of H2SO4×1000Volume of solution in mlOrNo of moles=0.01×100 1000=0.001 mol

We know that 
No of molecules in one mole = 6.022×1023
Therefore, no of molecules in 0.001 mol = 0.001​×6.022​×1023, i.e 0.006 ​×1023molecules.