Answer:
The answer to the question is
The source of the nitro- gen and oxygen atoms is from the atmosphere
Explanation:
When gasoline burns oxygen from the atmosphere supports the combustion reaction.
For example the internal combustion engine of a motor vehicle pulls in air from the surrounding atmosphere to make use of the oxygen in aiding the combustion of the gasoline to drive the pistons that ultimately moves the vehicle. The air from which the oxygen is absorbed also contains more amount of Nitrogen by percentage than oxygen. The nitrogen therefore enters into the combustion reaction that eventually produces nitrogen oxide and nitrogen dioxide
The answer of the question is C. Magnetic fields
Answer & Explanation:
The law of multiple proportion states that two elements A and B can react with each other to form multiple compounds while one of the two elements remain fixed.
For Example
Hydrogen reacts with oxygen to form:
Water (H2O)
Hydrogen peroxide (H2O2)
<u>Explanation:</u>
Molecular formula is the chemical formula which depicts the actual number of atoms of each element present in the compound.
Empirical formula is the simplest chemical formula which depicts the whole number of atoms of each element present in the compound.
In both the formulas, the nature of atoms remains the same but the number differs.
For Example: The molecular formula of oxalic acid is
but the empirical formula of oxalic acid is 
To calculate the molecular formula, we need to find the valency which is multiplied by each element to get the molecular formula.
The equation used to calculate the valency is:

The empirical mass can be calculated from empirical formula and molar mass must be known.
The most common type of fluoride found in toothpaste is part of the compound sodium fluoride which has the chemical formula NaF