[Fortify]

CaCO3 + H2SO4 -> CaSO4 + CO2 + H2O

Ratio is 1 : 1 : 1 : 1 : 1

n(CaCO3) = m / mm = 3.00 / (40.08+14.01+16+16+16) = 3.00 / 102.9 = 0.029385836

N(CaCO3) = 0.03mol

Since the molar ratio is 1 : 1 : 1 : 1 : 1, all the will have the same moles.

Therefore:
n(CaCO3) = n(H2SO4) = n(CaSO4) = n(CO2) = n(H2O)

A)
n(H2SO4) = m / mm

m(H2SO4) = n(H2SO4) * mm = 0.03 * 98.086 = 2.94258g

m(H2SO4) = 2.94g

B)
n(CO2) = m / mm

m(CO2) = n(CO2) * mm = 0.03 * 44.01 =1.3203g

m(CO2) = 1.32g

C)
n(CaSO4) = m / mm

m(CaSO4) = n(CaSO4) * mm = 0.03 * 136.51 = 4.0953G

m(CaSO4) = 4.10g