To find the mass of H2SO4, we first need to calculate the molar mass of H2SO4.

H2SO4:

2 Hydrogen (H) atoms each with a molar mass of approximately 1 g/mol1 Sulfur (S) atom with a molar mass of approximately 32 g/mol4 Oxygen (O) atoms each with a molar mass of approximately 16 g/mol

Adding these together, we get the molar mass of H2SO4:
2(1) + 32 + 4(16) = 2 + 32 + 64 = 98 g/mol

Now, let's find the number of moles of H2SO4 present in V(SO3) = 0.5 moles:
As the ratio of moles of H2SO4 to moles of SO3 is 1:1 in the chemical reaction, the number of moles of H2SO4 will also be 0.5 moles.

Now, we can calculate the mass of H2SO4 in 0.5 moles:
Mass = Number of moles Molar mass
Mass = 0.5 moles 98 g/mol = 49 g

Therefore, the mass of H2SO4 present in the given quantity of SO3 is 49 grams.