question. 2H2+O2→2H2O There are four atoms of hydrogen ( H ) before the reaction. How many atoms of hydrogen are present after the reaction?

Answer 1

In the reaction \(2H_2 + O_2 \rightarrow 2H_2O\), there are indeed four hydrogen atoms (from the two \(H_2\) molecules) before the reaction.

After the reaction, the product \(2H_2O\) contains hydrogen as well. Each water molecule (\(H_2O\)) contains two hydrogen atoms, and since there are two water molecules produced, the total number of hydrogen atoms after the reaction is:

\[ 2 \text{ (water molecules)} \times 2 \text{ (H atoms per molecule)} = 4 \text{ H atoms} \]

Therefore, there are still four hydrogen atoms present after the reaction. The number of hydrogen atoms is conserved in this reaction.