A.
The first energy level has 2 electrons, the second has 8, and the third has 4
Answer: 
Explanation:
Combustion is a chemical reaction in which hydrocarbons are burnt in the presence of oxygen to give carbon dioxide and water.
According to the law of conservation of mass, mass can neither be created nor be destroyed. Thus the mass of products formed must be equal to the mass of reactants taken. In order to get the same mass on both sides, the atoms of each element must be balanced on both sides of the chemical equation.
The balanced combustion reaction is,:

Heya
ques is what is cellular respiration?
the ans is Exchanging O2 for CO2 in the blood within the lungs.
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