I need help can someone please explain to me why this B is the correct answer I have a photo of the question I know B is the correct answer I just need help knowing why it’s B

9 g

Explanation:

Chemical equation:

CH₄ + 2O₂    →       CO₂ + 2H₂O

4        16                 11         9

4+16 = 20               11+9 = 20

9 gram of water must be produced because according to law of conservation of mass, mass neither created nor destroyed thus on both side of equation mass must be same.

Law of conservation of mass:

According to the law of conservation mass, mass can neither be created nor destroyed in a chemical equation.

This law was given by French chemist  Antoine Lavoisier in 1789. According to this law mass of reactant and mass of product must be equal, because masses are not created or destroyed in a chemical reaction.

For example:

6CO₂ + 6H₂O + energy → C₆H₁₂O₆ + 6O₂

there are six carbon atoms, eighteen oxygen atoms and twelve hydrogen atoms on the both side of equation so this reaction followed the law of conservation of mass.

it means there are 3 atoms of oxygen