Question

which of the following equations demonstrates the law of conservation of mass? (1 point)
o ch + o₂ → co₂ + h₂o
o ch₄ + o₂ → co₂ + h₂o
o ch₄ + o₂ → co₂ + ho
o ch₄ + o₂ → c + 2h₂o

Explanation:

Step1: Recall Law of Conservation of Mass

The law states that the total mass of reactants equals the total mass of products, which means the number of atoms of each element must be the same on both sides of a chemical - equation.

Step2: Analyze first equation $CH + O_2

ightarrow CO_2+H_2O$
The reactant side has 1 carbon, 1 hydrogen and 2 oxygen atoms. The product side has 1 carbon, 2 hydrogen and 3 oxygen atoms. Atoms are not balanced, so it does not follow the law.

Step3: Analyze second equation $CH_4 + O_2

ightarrow CO_2+H_2O$
Reactant side: 1 carbon, 4 hydrogen, 2 oxygen. Product side: 1 carbon, 2 hydrogen, 3 oxygen. Atoms are not balanced.

Step4: Analyze third equation $CH_4+O_2

ightarrow CO_2 + HO$
The formula $HO$ is incorrect (should be $H_2O$), and also the atom counts are not balanced. Reactant side has 1 carbon, 4 hydrogen, 2 oxygen. Product side has 1 carbon, 1 hydrogen, 3 oxygen.

Step5: Analyze fourth equation $CH_4+O_2

ightarrow C + 2H_2O$
Reactant side: 1 carbon, 4 hydrogen, 2 oxygen. Product side: 1 carbon, 4 hydrogen, 2 oxygen. Atoms of each element are balanced on both sides.

Answer:

$CH_4+O_2
ightarrow C + 2H_2O$