The second approach is correct. The other two approaches are not correct because they are incomplete; first approach would have been right IF the 6.0 ppm was MEASURED in hexane. Third approach cannot be right since it calculates moles and grams but not L.
1) All matter is made of atoms. 2) Atoms are indivisible and indestructible.
The answer is 
. A magnesium atom has 12 protons and an arrangement of [2, 8, 2]. When you lose two electrons, arrangement becomes [2,8] and the atom becomes a positively charged ion
1kg of water has greater internal energy compared to 1g of water because 1kg of water has more mass.
Using PV = nRT, we can calculate the moles of the sample.
874 mmHg = 116,524 Pa
n = PV/RT
n = 116,524 x 294 x 10⁻⁶ / 8.314 x (140 + 273)
n = 9.98 x 10⁻³ mol
moles = mass / Mr
Mr = 0.271/9.98 x 10⁻³
Mr = 27.2
Mass of empirical formula = 14
Repeat units = 27.2 / 14 ≈ 2
Formula of substance:
C₂H₄
Combustion equation:
C₂H₄ + 3O₂ → 2CO₂ + 2H₂O
1 mole produces 2 moles of CO₂, so 3 moles will produce 6 moles CO₂
