Question

the reactants and products of photosynthesis are made of the same amounts of hydrogen, carbon, and oxygen atoms. when 6 molecules of carbon dioxide gas (co₂) react with 6 molecules of water (h₂o), the atoms in those molecules are rearranged to produce 1 molecule of glucose (c₆h₁₂o₆) and 6 molecules of oxygen gas (o₂). which chemical equation is balanced and represents the overall process of photosynthesis? co₂ + h₂o → c₆h₁₂o₆ + 6o₂ co₂ + 6h₂o → 6c₆h₁₂o₆ + o₂ 6co₂ + 6h₂o → 6c₆h₁₂o₆ + 6o₂ 6co₂ + 6h₂o → c₆h₁₂o₆ + 6o₂

Explanation:

Step1: Count atoms in reactants

In 6 molecules of $CO_2$, there are 6 carbon atoms and 12 oxygen atoms. In 6 molecules of $H_2O$, there are 12 hydrogen atoms and 6 oxygen atoms. So in total for reactants, 6 C, 12 H, 18 O.

Step2: Count atoms in products for each option

• Option 1: In $C_6H_{12}O_6+6O_2$, 6 C, 12 H, 18 O. But coefficient of $CO_2$ is 1 in reactants which is wrong as per problem.
• Option 2: In $6C_6H_{12}O_6 + O_2$, too many C, H and wrong O count compared to reactants.
• Option 3: In $6C_6H_{12}O_6+6O_2$, too many C and H compared to reactants.
• Option 4: In $C_6H_{12}O_6+6O_2$, 6 C, 12 H, 18 O and coefficients of reactants ($6CO_2 + 6H_2O$) match given amounts in problem.

Answer:

$6CO_2 + 6H_2O\longrightarrow C_6H_{12}O_6+6O_2$ (the fourth option)