Question

in which chemical equation is the number of atoms in the reactants the same as the number of atoms in the products? (1 point) ch₄ + o₂ → co₂ + 2h₂o co₂ + h₂o → ch₂oh + o₂ li₂co₃ → lio + co₂ zn + 2hcl → h₂ + zncl₂

Explanation:

Step1: Check atom - conservation for each equation

For the equation $\text{Zn}+2\text{HCl}
ightarrow\text{H}_2 + \text{ZnCl}_2$:

• Reactants: 1 Zn atom, 2 H atoms, 2 Cl atoms.
• Products: 1 Zn atom, 2 H atoms, 2 Cl atoms.

For the equation $\text{Li}_2\text{CO}_3
ightarrow\text{Li}_2\text{O}+\text{CO}_2$:

• Reactants: 2 Li atoms, 1 C atom, 3 O atoms.
• Products: 2 Li atoms, 1 C atom, 3 O atoms.

For the equation $\text{CO}_2+\text{H}_2\text{O}
ightarrow\text{CH}_2\text{OH}+\text{O}_2$:

• Reactants: 1 C atom, 2 H atoms, 3 O atoms.
• Products: 1 C atom, 2 H atoms, 3 O atoms (but this equation is not balanced as the oxygen - atom distribution is incorrect in terms of chemical reaction principles).

For the equation $\text{CH}_4+\text{O}_2
ightarrow\text{CO}_2 + 2\text{H}_2\text{O}$:

• Reactants: 1 C atom, 4 H atoms, 2 O atoms.
• Products: 1 C atom, 4 H atoms, 4 O atoms (this equation is not balanced).

Step2: Determine the balanced equation

The balanced equations $\text{Zn}+2\text{HCl}
ightarrow\text{H}_2+\text{ZnCl}_2$ and $\text{Li}_2\text{CO}_3
ightarrow\text{Li}_2\text{O}+\text{CO}_2$ follow the law of conservation of mass (number of atoms in reactants = number of atoms in products). But considering the chemical - reaction feasibility, we focus on the common - sense balanced equations. The equation $\text{Zn}+2\text{HCl}
ightarrow\text{H}_2+\text{ZnCl}_2$ is a typical single - displacement reaction and is balanced correctly.

Answer:

$\text{Zn}+2\text{HCl}
ightarrow\text{H}_2+\text{ZnCl}_2$