Question

conservation quick check
which of the following equations demonstrates the law of conservation of mass? (1 point)
○ (ch_4 + o_2
ightarrow co_2 + h_2o)
● (ch_4 + o_2
ightarrow c + 2h_2o)
○ (ch + o_2
ightarrow co_2 + h_2o)
○ (ch_4 + o_2
ightarrow co_2 + ho)

Explanation:

Step1: Recall law of conservation of mass

The law states that mass is neither created nor destroyed in a chemical reaction. So, the number of atoms of each element on the reactant side must equal the number of atoms of that element on the product side.

Step2: Analyze first equation

For $CH_4 + O_2
ightarrow CO_2+H_2O$, on the reactant side: 1 C, 4 H, 2 O. On the product side: 1 C, 2 H, 3 O. Not balanced.

Step3: Analyze second equation

For $CH_4 + O_2
ightarrow C + 2H_2O$, on the reactant side: 1 C, 4 H, 2 O. On the product side: 1 C, 4 H, 2 O. Balanced.

Step4: Analyze third equation

For $CH+O_2
ightarrow CO_2 + H_2O$, $CH$ is not a common - known stable compound formula. Also, atom counts don't match.

Step5: Analyze fourth equation

For $CH_4+O_2
ightarrow CO_2 + HO$, $HO$ is not a correct chemical formula. Also, atom counts don't match.

Answer:

$CH_4 + O_2
ightarrow C + 2H_2O$