<span>The number of molecules of each gas must be equal since 1 mol of any gas needs to contain 6.02x10^23 molecules. So 1mol O</span>₂ and 1mol CO both need to contain 6.02x10^23 molecules
Fire is actually a chemical reaction. It's an oxidation reaction to be specific. When wood gets hot enough (the part of the wood that is burning) the large hydrocarbons break down to charred solids and a gas. The gas is what reacts with oxygen in the atmosphere to produced light, CO2 and H2O.
The empirical formula gives the relative ratio of atoms in each element. Therefore, it simplifies the whole numbers. For example C2H6 can be reduced to CH3 because they share the greatest common factor (2). The answer to this question would be #1. C4H10 can be reduced to C2H5 because 4 and 10 are both divisible by 2. C2H5 can not be reduced any further. All of the other options do not have a greatest common factor making them a empirical formula.
Barium fluoride (BaF2) - Also known as Barium(II) fluoride - because it's a combination of two different kinds of ions (binary = two).