Reaction of sodium with water
Sodium metal reacts rapidly with water to form a colourless solution of sodium hydroxide (NaOH) and hydrogen gas (H2). The resulting solution is basic because of the dissolved hydroxide. The reaction is exothermic. During the reaction, the sodium metal may well become so hot that it catches fire and burns with a characteristic orange colour. The reaction is slower than that of potassium (immediately below sodium in the periodic table), but faster than that of lithium (immediately above sodium in the periodic table).
2Na(s) + 2H2O → 2NaOH(aq) + H2(g)
Answer: The ratio of carbon dioxide molecules to oxygen molecules is 20 :31
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 has to be equal to the mass of reactants. The number of atoms of each element has to be same on reactant and product side. Thus chemical equations are balanced.
The balanced combustion reaction is,:

Thus the ratio of carbon dioxide molecules to oxygen molecules is 20 : 31
Atomic number refers to the proton number of the atom itself. Number of electrons in an atom (an atom that is not reacted with any other molecules / Just the atom alone), is the same as the number of protons, because each electron has 1 negative charge, and each proton 1 positive charge, where they cancel out on each other to become a neutral charge.
So, when atomic number is 6, proton number is also 6, and number of electrons will also be 6 in that atom.
Hope this helps! :)
Remembering the periodic table, Fe is iron and O is oxygen. The elements that combine to create rust are iron and oxygen, with the chemical compound being (Iron)2(Oxygen)3.