CBSE Class 10 Answered
A chemical equation is balanced when the number of atoms of each type on each side of the equation is the same. Which means if you have 12 oxygen on the left hand side of the equation, you must have 12 oxygen on the right hand side, if there are 4 carbons on the left, there must 4 carbons on the right, and so on. This is because of the law of conservation of mass - you can 't make or destroy atoms during a chemical reaction.
For example,
Unbalanced Equation:- C3H8 + O2 ---> H2O + CO2
There are three carbons on the left, but only one on the right.
There are eight hydrogens on the left but only two on the right.
There are two oxygens on the left but three on the right.
Balanced Equation:- C3H8 + 5O2 ---> 4H2O + 3CO2