calculate total number of moles of atoms present in 49g H2SO4
Atomic mass of one molecule of H2SO4 is 98 Atomic mass unit.
Atomic mass of one mole of H2SO4 is 98 grams.
So 98 grams of H2SO4 contains 1 mole of H2SO4 molecule i.e., 7 moles atoms.
So, by applying the basic maths, we get
49 grams of H2SO4 contains 1/2 mole of H2SO4 molecule i.e., 3.5 moles atoms.
Hope it helps.