Step-by-step explanation:
1) Complete combustion of propane gives carbon dioxide gas and water vapors.
The balanced chemical equation is given as:
![C_3H_8(g)+5O_2(g)\rightarrow 3CO_2(g)+4H_2O(g)](https://img.qammunity.org/2021/formulas/chemistry/college/865h9okn5qhfulbsjyqbd6jwzyciefgs1m.png)
Number of carbon atoms on reactant side = 3
Number of hydrogen atoms on reactant side = 8
Number of oxygen atoms on reactant side = 10
Number of carbon atoms on the product side = 3
Number of hydrogen atoms on the product side = 8
Number of oxygen atoms on the product side = 10
On both the sides numbers, all elements remained the same which indicates that matter remains conserved during the course of a chemical reaction.
2) Incomplete combustion of propane gives carbon dioxide gas, carbon monoxide gas, and water vapors.
The balanced chemical equation is given as:
![2C_3H_8(g)+9O_2(g)\rightarrow 4CO_2(g)+2CO(g)+8H_2O(g)](https://img.qammunity.org/2021/formulas/chemistry/high-school/qskxp1rmkkbp2bj080sgrb4prv3zoigw0g.png)
Number of carbon atoms on reactant side = 6
Number of hydrogen atoms on reactant side = 16
Number of oxygen atoms on reactant side = 18
Number of carbon atoms on the product side = 6
Number of hydrogen atoms on the product side = 16
Number of oxygen atoms on the product side = 18
On both the sides numbers, all elements remained the same which indicates that matter remains conserved during the course of a chemical reaction.