Atomic number refers to the number of protons within the nuclei of an element's atoms (and therefore the number of electrons) while mass number refers to the number of protons and neutrons within the nucleus.
The atomic mass is the average of the isotopes of the element meaning most averages of isotopes will not be whole numbers
moles NaOH = c · V = 0.1973 mmol/mL · 29.43 mL = 5.806539 mmol
moles H2SO4 = 5.806539 mmol NaOH · 1 mmol H2SO4 / 2 mmol NaOH = 2.9032695 mmol
Hence
[H2SO4]= n/V = 2.9032695 mmol / 32.42 mL = 0.08955 M
The answer to this question is [H2SO4] = 0.08955 M
