Final answer:
The compound with the smallest formula mass is H₂O (water), with a formula mass of 18.02 g/mol.
Step-by-step explanation:
The formula mass of a compound can be determined by adding up the atomic masses of all the atoms in the compound. In this case, we need to calculate the formula mass for each of the given compounds: NO₂, SO₂, SiO₂, CO₂, H₂O.
Let's calculate the formula mass for each of them:
- NO₂: Nitrogen (N) has an atomic mass of 14.01 g/mol and Oxygen (O) has an atomic mass of 16.00 g/mol. So, the formula mass of NO₂ = (14.01 g/mol) + 2(16.00 g/mol) = 46.01 g/mol.
- SO₂: Sulfur (S) has an atomic mass of 32.07 g/mol and Oxygen (O) has an atomic mass of 16.00 g/mol. So, the formula mass of SO₂ = (32.07 g/mol) + 2(16.00 g/mol) = 64.07 g/mol.
- SiO₂: Silicon (Si) has an atomic mass of 28.09 g/mol and Oxygen (O) has an atomic mass of 16.00 g/mol. So, the formula mass of SiO₂ = (28.09 g/mol) + 2(16.00 g/mol) = 60.09 g/mol.
- CO₂: Carbon (C) has an atomic mass of 12.01 g/mol and Oxygen (O) has an atomic mass of 16.00 g/mol. So, the formula mass of CO₂ = (12.01 g/mol) + 2(16.00 g/mol) = 44.01 g/mol.
- H₂O: Hydrogen (H) has an atomic mass of 1.01 g/mol and Oxygen (O) has an atomic mass of 16.00 g/mol. So, the formula mass of H₂O = 2(1.01 g/mol) + 16.00 g/mol = 18.02 g/mol.
Comparing the formula masses, we can see that H₂O has the smallest formula mass of 18.02 g/mol, as it contains the lightest atoms and has the lowest total atomic mass.