To determine the reactants for the given reaction where the products are [tex]\( CO_2 \)[/tex] (carbon dioxide) and [tex]\( 2 H_2O \)[/tex] (water), we need to consider the conservation of mass and the elemental composition involved.
Step-by-step analysis:
1. Identify the elements in the products:
- [tex]\( CO_2 \)[/tex]: Contains Carbon (C) and Oxygen (O).
- [tex]\( 2 H_2O \)[/tex]: Contains Hydrogen (H) and Oxygen (O).
2. Conservation of Mass:
- According to the law of conservation of mass, the elements present in the products must also be present in the reactants. This means the reactants must contain Carbon (C), Hydrogen (H), and Oxygen (O).
3. Rule out options based on the conservation of mass:
- Option A: The reactants include substances with only [tex]\( C \)[/tex], [tex]\( O \)[/tex], and [tex]\( H \)[/tex] atoms.
- This is potentially correct, as both the products [tex]\( CO_2 \)[/tex] and [tex]\( 2 H_2O \)[/tex] contain these elements.
- Option B: The reactants include [tex]\( CO_2 \)[/tex] and [tex]\( H_2O \)[/tex].
- This is unlikely because if [tex]\( CO_2 \)[/tex] and [tex]\( H_2O \)[/tex] were reactants, it would not change in the reaction, and there wouldn't be a chemical reaction happening, just a physical change.
- Option C: The reactants do not include any [tex]\( C \)[/tex], [tex]\( O \)[/tex], or [tex]\( H \)[/tex] atoms.
- This is incorrect because the products contain [tex]\( C \)[/tex], [tex]\( O \)[/tex], and [tex]\( H \)[/tex], so the reactants must also contain these elements.
- Option D: The reactants are also [tex]\( CO_2 \)[/tex] and [tex]\( H_2O \)[/tex].
- This is incorrect for the same reason as Option B. A chemical reaction implies a change in the reactants to form new products, not identical substances.
4. Conclusion:
- Based on the conservation of mass and the requirement for the reactants to contain the same elements as the products, the most logical answer is:
A. The reactants include substances with only [tex]\( C \)[/tex], [tex]\( O \)[/tex], and [tex]\( H \)[/tex] atoms.
This conclusion ensures that the reactants can form the given products, thereby adhering to the law of conservation of mass and indicating the presence of only the necessary elements [tex]\( C \)[/tex], [tex]\( O \)[/tex], and [tex]\( H \)[/tex] in the reactants.
