To determine which chemical equation has water (H₂O) as a reactant, let's examine each given equation:
A. [tex]\( CO_2 + O_2 + \text{energy} \rightarrow C_6H_{12}O_6 + O_2 \)[/tex]
- Reactants: [tex]\( CO_2 \)[/tex], [tex]\( O_2 \)[/tex]
- Products: [tex]\( C_6H_{12}O_6 \)[/tex], [tex]\( O_2 \)[/tex]
- Water (H₂O) is not present as a reactant.
B. [tex]\( Na + H_2O \rightarrow NaOH + H_2 \)[/tex]
- Reactants: [tex]\( Na \)[/tex], [tex]\( H_2O \)[/tex]
- Products: [tex]\( NaOH \)[/tex], [tex]\( H_2 \)[/tex]
- Water (H₂O) is a reactant in this equation.
C. [tex]\( Na + Cl \rightarrow NaCl \)[/tex]
- Reactants: [tex]\( Na \)[/tex], [tex]\( Cl \)[/tex]
- Products: [tex]\( NaCl \)[/tex]
- Water (H₂O) is not present as a reactant.
D. [tex]\( H_2 + O_2 \rightarrow H_2O \)[/tex]
- Reactants: [tex]\( H_2 \)[/tex], [tex]\( O_2 \)[/tex]
- Products: [tex]\( H_2O \)[/tex]
- Water (H₂O) is a product in this equation, not a reactant.
From these examinations, we can see that option B is the one where water (H₂O) is a reactant. Therefore, the correct answer is:
B. [tex]\( Na + H_2O \rightarrow NaOH + H_2 \)[/tex]
