Answer: The sum of the coefficients needed to balance the combustion reaction of methane is 6.
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 chemical equation for combustion of methane will be :

The coefficient foer methane is 1 , 2 for oxygen , 1 for carbon dioxide and 2 for water. The sum is 6.
They are called the terrestrial planets and are smaller than the others. They are he hottest planets and closest to the sun and take less time to rotate the sun.
Given :
Mass of oxygen containing carbon monoxide (CO) is 2.666 gram .
To Find :
How many grams of carbon (C) would be present in carbon monoxide (CO) that contains 2.666 grams of oxygen (O) .
Solution :
By law of constant composition , a given chemical compound always contains its component elements in fixed ratio (by mass) and does not depend on its source and method of preparation.
So , volume of solution does not matter .
Moles of oxygen ,
.
Now , molecule of CO contains 1 mole of C .
So , moles of C is also 0.167 mole .
Mass of carbon ,
.
Therefore , mass of carbon is 2 grams .
Hence , this is the required solution .