To determine which chemical equation has the same number of atoms in the reactants as in the products, we need to count the atoms on both sides for each equation.
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CO2 + H2O → CH2OH + O2
- Reactants: C=1, O=3, H=2 (Total = 6)
- Products: C=1, O=3, H=2 (Total = 6)
- Atoms are balanced.
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Zn + 2HCl → H2 + ZnCl2
- Reactants: Zn=1, H=2, Cl=2 (Total = 5)
- Products: Zn=1, H=2, Cl=2 (Total = 5)
- Atoms are balanced.
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Li2CO3 → LiO + CO2
- Reactants: Li=2, C=1, O=3 (Total = 6)
- Products: Li=1, O=1, C=1, O=2 (Total = 4)
- Atoms are not balanced.
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CH4 + O2 → CO2 + 2H2O
- Reactants: C=1, H=4, O=2 (Total = 7)
- Products: C=1, H=4, O=4 (Total = 9)
- Atoms are not balanced.
From this analysis, the first two equations are balanced with regard to the total number of atoms.
However, since you asked for just one equation, the answer is:
CO2 + H2O → CH2OH + O2 (and also Zn + 2HCl → H2 + ZnCl2).