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Chemistry

Chemistry Help: Interpret Coefficients As Mole Ratios

Review real example questions for Interpret Coefficients As Mole Ratios in Chemistry.

Question 1

Ammonia forms according to N2+3H2→2NH3.\text{N}_2 + 3\text{H}_2 \rightarrow 2\text{NH}_3.N2​+3H2​→2NH3​. What is the mole ratio of NH3\text{NH}_3NH3​ to H2\text{H}_2H2​?

  1. 2:3
  2. 3:2
  3. 2:1
  4. 3:1
Explanation: This question tests your understanding that coefficients in balanced chemical equations represent mole ratios—the proportional relationships between amounts of reactants consumed and products formed in a chemical reaction. The coefficients in a balanced equation (the numbers in front of chemical formulas) tell you the ratio of MOLES of each substance involved in the reaction: in N2+3H2→2NH3\text{N}_2 + 3\text{H}_2 \rightarrow 2\text{NH}_3N2​+3H2​→2NH3​, the coefficients 1, 3, and 2 mean that 1 mole of nitrogen reacts with 3 moles of hydrogen to produce 2 moles of ammonia. This ratio is the fundamental relationship—it means for every 3 moles of H2\text{H}_2H2​ consumed, exactly 1 mole of N2\text{N}_2N2​ is consumed and 2 moles of NH3\text{NH}_3NH3​ are produced. The ratio stays constant no matter how much you scale it: 2 moles of N2\text{N}_2N2​ with 6 moles of H2\text{H}_2H2​ makes 4 moles of NH3\text{NH}_3NH3​ (doubled), or 0.5 moles of N2\text{N}_2N2​ with 1.5 moles of H2\text{H}_2H2​ makes 1 mole of NH3\text{NH}_3NH3​ (halved)—the 1:3:2 ratio is preserved! In this equation, the mole ratio of NH3\text{NH}_3NH3​ to H2\text{H}_2H2​ is extracted from their coefficients: NH3\text{NH}_3NH3​ has 2 and H2\text{H}_2H2​ has 3, so it's 2:3, meaning 2 moles of NH3\text{NH}_3NH3​ per 3 moles of H2\text{H}_2H2​. Choice A correctly interprets the coefficients as the mole ratio between NH3\text{NH}_3NH3​ and H2\text{H}_2H2​, stating 2:3. A distractor like choice B (3:2) might swap the order, but the question specifies NH3\text{NH}_3NH3​ to H2\text{H}_2H2​, which is 2:3—pay attention to which comes first. Reading mole ratios from balanced equations: (1) Locate the two substances you're comparing in the equation. (2) Read their coefficients (the numbers in front—if no number is written, the coefficient is 1). (3) Write the ratio: [coefficient of first substance] : [coefficient of second substance]. Using mole ratios as conversion factors: mole ratios let you predict amounts! If you know how many moles of one substance you have, you can calculate moles of another using the ratio.

Question 2

For the synthesis of ammonia, the balanced equation is N2+3H2→2NH3\mathrm{N_2 + 3H_2 \rightarrow 2NH_3}N2​+3H2​→2NH3​. According to the coefficients, how many moles of H2\mathrm{H_2}H2​ react per 1 mole of N2\mathrm{N_2}N2​?

  1. 1 mol H2\mathrm{H_2}H2​
  2. 2 mol H2\mathrm{H_2}H2​
  3. 3 mol H2\mathrm{H_2}H2​
  4. 6 mol H2\mathrm{H_2}H2​
Explanation: This question tests your understanding that coefficients in balanced chemical equations represent mole ratios—the proportional relationships between amounts of reactants consumed and products formed in a chemical reaction. The coefficients in a balanced equation (the numbers in front of chemical formulas) tell you the ratio of MOLES of each substance involved in the reaction: in 2H2+O2→2H2O2H2 + O2 \rightarrow 2H2O2H2+O2→2H2O, the coefficients 2, 1, and 2 mean that 2 moles of hydrogen gas react with 1 mole of oxygen gas to produce 2 moles of water. This ratio is the fundamental relationship—it means for every 1 mole of O2 consumed, exactly 2 moles of H2 are consumed and exactly 2 moles of H2O are produced. The ratio stays constant no matter how much you scale it: 4 moles H2 with 2 moles O2 makes 4 moles H2O (doubled), or 1 mole H2 with 0.5 moles O2 makes 1 mole H2O (halved)—the 2:1:2 ratio is preserved! In the given equation N2+3H2→2NH3N2 + 3H2 \rightarrow 2NH3N2+3H2→2NH3, the coefficient for H2 is 3 and for N2 is 1, so per 1 mole of N2, 3 moles of H2 react, directly from the 1:3 ratio of N2 to H2. Choice C correctly interprets the coefficients as the mole ratio between the specified substances. A distractor like choice B might misread the ratio as 2 moles from the product side, but focus on the reactant coefficients and the 'per 1 mole of N2' phrasing to avoid confusing it with the NH3 coefficient. Reading mole ratios from balanced equations: (1) Locate the two substances you're comparing in the equation. (2) Read their coefficients (the numbers in front—if no number is written, the coefficient is 1). (3) Write the ratio: [coefficient of first substance] : [coefficient of second substance]. Using mole ratios as conversion factors: mole ratios let you predict amounts! If you know how many moles of one substance you have, you can calculate moles of another using the ratio—they're not just decorative numbers, they're the mathematical relationship between substances in the reaction!

Question 3

In the balanced equation 2KClO3→2KCl+3O2,\mathrm{2KClO_3 \rightarrow 2KCl + 3O_2},2KClO3​→2KCl+3O2​, what is the mole ratio of KClO3\mathrm{KClO_3}KClO3​ to O2\mathrm{O_2}O2​?

  1. 3:23:23:2
  2. 2:32:32:3
  3. 2:12:12:1
  4. 1:31:31:3
Explanation: This question tests your understanding that coefficients in balanced chemical equations represent mole ratios—the proportional relationships between amounts of reactants consumed and products formed in a chemical reaction. The coefficients in a balanced equation (the numbers in front of chemical formulas) tell you the ratio of MOLES of each substance involved in the reaction: in 2H2 + O2 → 2H2O, the coefficients 2, 1, and 2 mean that 2 moles of hydrogen gas react with 1 mole of oxygen gas to produce 2 moles of water. This ratio is the fundamental relationship—it means for every 1 mole of O2 consumed, exactly 2 moles of H2 are consumed and exactly 2 moles of H2O are produced. The ratio stays constant no matter how much you scale it: 4 moles H2 with 2 moles O2 makes 4 moles H2O (doubled), or 1 mole H2 with 0.5 moles O2 makes 1 mole H2O (halved)—the 2:1:2 ratio is preserved! In the given equation 2KClO3 → 2KCl + 3O2, the coefficient for KClO3 is 2 and for O2 is 3, so the mole ratio of KClO3 to O2 is 2:3, meaning 2 moles of KClO3 produce 3 moles of O2. Choice B correctly interprets the coefficients as the mole ratio between the specified substances. A distractor like choice A might reverse to 3:2, but always use the order asked—KClO3 to O2 means coefficient of KClO3 first (2) to O2 (3). Reading mole ratios from balanced equations: (1) Locate the two substances you're comparing in the equation. (2) Read their coefficients (the numbers in front—if no number is written, the coefficient is 1). (3) Write the ratio: [coefficient of first substance] : [coefficient of second substance]. Using mole ratios as conversion factors: mole ratios let you predict amounts! If you know how many moles of one substance you have, you can calculate moles of another using the ratio—they're not just decorative numbers, they're the mathematical relationship between substances in the reaction!

Question 4

Methane combusts according to the balanced equation: CH4+2O2→CO2+2H2O\mathrm{CH_4 + 2O_2 \rightarrow CO_2 + 2H_2O}CH4​+2O2​→CO2​+2H2​O According to the coefficients, how many moles of oxygen gas (O2\mathrm{O_2}O2​) are required per 1 mol of methane (CH4\mathrm{CH_4}CH4​)?

  1. 1 mol O2\mathrm{O_2}O2​
  2. 2 mol O2\mathrm{O_2}O2​
  3. 4 mol O2\mathrm{O_2}O2​
  4. Depends on temperature, not coefficients
Explanation: This question tests your understanding that coefficients in balanced chemical equations represent mole ratios—the proportional relationships between amounts of reactants consumed and products formed in a chemical reaction. The coefficients in a balanced equation (the numbers in front of chemical formulas) tell you the ratio of MOLES of each substance involved in the reaction: in CH₄ + 2O₂ → CO₂ + 2H₂O, the coefficients 1, 2, 1, and 2 mean that 1 mole of methane reacts with 2 moles of oxygen gas to produce 1 mole of carbon dioxide and 2 moles of water. From the equation CH₄ + 2O₂ → CO₂ + 2H₂O, the coefficient of CH₄ is 1 (when no number is shown, it's 1) and the coefficient of O₂ is 2, so the ratio is 1:2, meaning 1 mole of CH₄ requires exactly 2 moles of O₂. Choice B correctly states that 2 mol O₂ are required per 1 mol CH₄, directly matching the 1:2 ratio from the coefficients. The other choices suggest incorrect amounts (1 mol, 4 mol) or incorrectly claim the ratio depends on temperature rather than the balanced equation coefficients. Reading mole ratios from balanced equations: (1) Locate the two substances you're comparing in the equation. (2) Read their coefficients (the numbers in front—if no number is written, the coefficient is 1). (3) Write the ratio: [coefficient of first substance] : [coefficient of second substance]. The beauty of mole ratios is their scalability: if you have 5 moles of CH₄, you need 10 moles of O₂ (5 × 2 = 10), and if you have only 0.5 moles of CH₄, you need 1 mole of O₂ (0.5 × 2 = 1)—the 1:2 ratio always holds!

Question 5

Iron reacts with chlorine according to the balanced equation 2Fe+3Cl2→2FeCl3.2\text{Fe} + 3\text{Cl}_2 \rightarrow 2\text{FeCl}_3.2Fe+3Cl2​→2FeCl3​. What is the mole ratio of Fe\text{Fe}Fe to Cl2\text{Cl}_2Cl2​?

  1. 3:2
  2. 2:3
  3. 2:1
  4. 1:1
Explanation: This question tests your understanding that coefficients in balanced chemical equations represent mole ratios—the proportional relationships between amounts of reactants consumed and products formed in a chemical reaction. The coefficients in a balanced equation (the numbers in front of chemical formulas) tell you the ratio of MOLES of each substance involved in the reaction: in 2Fe+3Cl2→2FeCl32\text{Fe} + 3\text{Cl}_2 \rightarrow 2\text{FeCl}_32Fe+3Cl2​→2FeCl3​, the coefficients 2, 3, and 2 mean that 2 moles of Fe\text{Fe}Fe react with 3 moles of Cl2\text{Cl}_2Cl2​ to produce 2 moles of FeCl3\text{FeCl}_3FeCl3​. This ratio is the fundamental relationship—it means for every 2 moles of Fe\text{Fe}Fe consumed, exactly 3 moles of Cl2\text{Cl}_2Cl2​ are consumed and 2 moles of FeCl3\text{FeCl}_3FeCl3​ are produced. The ratio stays constant no matter how much you scale it: 4 moles Fe\text{Fe}Fe with 6 moles Cl2\text{Cl}_2Cl2​ makes 4 moles FeCl3\text{FeCl}_3FeCl3​ (doubled), or 1 mole Fe\text{Fe}Fe with 1.5 moles Cl2\text{Cl}_2Cl2​ makes 1 mole FeCl3\text{FeCl}_3FeCl3​ (halved)—the 2:3:22:3:22:3:2 ratio is preserved! In this equation, the mole ratio of Fe\text{Fe}Fe to Cl2\text{Cl}_2Cl2​ is extracted from their coefficients: Fe\text{Fe}Fe has 2 and Cl2\text{Cl}_2Cl2​ has 3, so it's 2:32:32:3, meaning 2 moles of Fe\text{Fe}Fe per 3 moles of Cl2\text{Cl}_2Cl2​. Choice B correctly interprets the coefficients as the mole ratio between Fe\text{Fe}Fe and Cl2\text{Cl}_2Cl2​, stating 2:32:32:3. A distractor like choice A (3:23:23:2) might reverse the substances, but confirm the order: it's Fe\text{Fe}Fe to Cl2\text{Cl}_2Cl2​, which is 2:32:32:3, not 3:23:23:2. Reading mole ratios from balanced equations: (1) Locate the two substances you're comparing in the equation. (2) Read their coefficients (the numbers in front—if no number is written, the coefficient is 1). (3) Write the ratio: [coefficient of first substance] : [coefficient of second substance]. Using mole ratios as conversion factors: mole ratios let you predict amounts! If you know how many moles of one substance you have, you can calculate moles of another using the ratio.

Question 6

The synthesis of ammonia is represented by the balanced equation N2+3H2→2NH3.\text{N}_2 + 3\text{H}_2 \rightarrow 2\text{NH}_3.N2​+3H2​→2NH3​. According to the coefficients, how many moles of H2\text{H}_2H2​ react per 1 mole of N2\text{N}_2N2​?

  1. 1 mol H2\text{H}_2H2​
  2. 2 mol H2\text{H}_2H2​
  3. 3 mol H2\text{H}_2H2​
  4. 6 mol H2\text{H}_2H2​
Explanation: This question tests your understanding that coefficients in balanced chemical equations represent mole ratios—the proportional relationships between amounts of reactants consumed and products formed in a chemical reaction. The coefficients in a balanced equation (the numbers in front of chemical formulas) tell you the ratio of MOLES of each substance involved in the reaction: in N₂ + 3H₂ → 2NH₃, the coefficients 1, 3, and 2 mean that 1 mole of nitrogen gas reacts with 3 moles of hydrogen gas to produce 2 moles of ammonia. This ratio is the fundamental relationship—it means for every 1 mole of N₂ consumed, exactly 3 moles of H₂ are consumed and exactly 2 moles of NH₃ are produced. The ratio stays constant no matter how much you scale it: 2 moles N₂ with 6 moles H₂ makes 4 moles NH₃ (doubled), or 0.5 moles N₂ with 1.5 moles H₂ makes 1 mole NH₃ (halved)—the 1:3:2 ratio is preserved! In this equation, the mole ratio of H₂ to N₂ is extracted from their coefficients: H₂ has 3 and N₂ has 1 (implied), so per 1 mole of N₂, 3 moles of H₂ react. Choice C correctly interprets the coefficients by stating 3 mol H₂ react per 1 mol N₂. A distractor like choice B (2 mol H₂) might confuse the product coefficient with the reactant, but remember, we're focusing on reactants here—check the equation sides carefully. Reading mole ratios from balanced equations: (1) Locate the two substances you're comparing in the equation. (2) Read their coefficients (the numbers in front—if no number is written, the coefficient is 1). (3) Write the ratio: [coefficient of first substance] : [coefficient of second substance]. Using mole ratios as conversion factors: mole ratios let you predict amounts! If you know how many moles of one substance you have, you can calculate moles of another using the ratio.

Question 7

In the balanced equation 4Fe+3O2→2Fe2O34 \mathrm{Fe} + 3 \mathrm{O}_2 \rightarrow 2 \mathrm{Fe}_2\mathrm{O}_34Fe+3O2​→2Fe2​O3​, what is the mole ratio of Fe2O3\mathrm{Fe}_2\mathrm{O}_3Fe2​O3​ to Fe\mathrm{Fe}Fe?

  1. 2:4
  2. 4:2
  3. 2:3
  4. 3:4
Explanation: This question tests your understanding that coefficients in balanced chemical equations represent mole ratios—the proportional relationships between amounts of reactants consumed and products formed in a chemical reaction. The coefficients in a balanced equation (the numbers in front of chemical formulas) tell you the ratio of MOLES of each substance involved in the reaction: in 4Fe+3O2→2Fe2O34 \mathrm{Fe} + 3 \mathrm{O}_2 \rightarrow 2 \mathrm{Fe}_2\mathrm{O}_34Fe+3O2​→2Fe2​O3​, the coefficients 4, 3, and 2 mean that 4 moles of iron react with 3 moles of oxygen to produce 2 moles of iron(III) oxide. This ratio is the fundamental relationship—it means for every 4 moles of Fe\mathrm{Fe}Fe consumed, exactly 3 moles of O2\mathrm{O}_2O2​ are consumed and 2 moles of Fe2O3\mathrm{Fe}_2\mathrm{O}_3Fe2​O3​ are produced. The ratio stays constant no matter how much you scale it: 8 moles of Fe\mathrm{Fe}Fe with 6 moles of O2\mathrm{O}_2O2​ makes 4 moles of Fe2O3\mathrm{Fe}_2\mathrm{O}_3Fe2​O3​ (doubled), or 2 moles of Fe\mathrm{Fe}Fe with 1.5 moles of O2\mathrm{O}_2O2​ makes 1 mole of Fe2O3\mathrm{Fe}_2\mathrm{O}_3Fe2​O3​ (halved)—the 4:3:2 ratio is preserved! In this equation, the mole ratio of Fe2O3\mathrm{Fe}_2\mathrm{O}_3Fe2​O3​ to Fe\mathrm{Fe}Fe is extracted from their coefficients: Fe2O3\mathrm{Fe}_2\mathrm{O}_3Fe2​O3​ has 2 and Fe\mathrm{Fe}Fe has 4, so it's 2:4 (or simplified 1:2, but the question uses unsimplified). Choice A correctly interprets the coefficients as the mole ratio between Fe2O3\mathrm{Fe}_2\mathrm{O}_3Fe2​O3​ and Fe\mathrm{Fe}Fe, stating 2:4. A distractor like choice B (4:2) reverses the order, but the question asks for Fe2O3\mathrm{Fe}_2\mathrm{O}_3Fe2​O3​ to Fe\mathrm{Fe}Fe, which is 2:4—always match the sequence. Reading mole ratios from balanced equations: (1) Locate the two substances you're comparing in the equation. (2) Read their coefficients (the numbers in front—if no number is written, the coefficient is 1). (3) Write the ratio: [coefficient of first substance] : [coefficient of second substance]. Using mole ratios as conversion factors: mole ratios let you predict amounts! If you know how many moles of one substance you have, you can calculate moles of another using the ratio.

Question 8

In the balanced decomposition reaction 2H2O2→2H2O+O22\text{H}_2\text{O}_2 \rightarrow 2\text{H}_2\text{O} + \text{O}_22H2​O2​→2H2​O+O2​, what is the mole ratio of H2O\text{H}_2\text{O}H2​O to O2\text{O}_2O2​?

  1. 2:1
  2. 1:2
  3. 2:2
  4. 2:4
Explanation: This question tests your understanding that coefficients in balanced chemical equations represent mole ratios—the proportional relationships between amounts of reactants consumed and products formed in a chemical reaction. The coefficients in a balanced equation (the numbers in front of chemical formulas) tell you the ratio of MOLES of each substance involved in the reaction: in 2H2O2→2H2O+O22\text{H}_2\text{O}_2 \rightarrow 2\text{H}_2\text{O} + \text{O}_22H2​O2​→2H2​O+O2​, the coefficients 2, 2, and 1 mean that 2 moles of hydrogen peroxide decompose to produce 2 moles of water and 1 mole of oxygen. This ratio is the fundamental relationship—it means for every 2 moles of H2O2\text{H}_2\text{O}_2H2​O2​ decomposed, exactly 2 moles of H2O\text{H}_2\text{O}H2​O and 1 mole of O2\text{O}_2O2​ are produced. The ratio stays constant no matter how much you scale it: 4 moles H2O2\text{H}_2\text{O}_2H2​O2​ makes 4 moles H2O\text{H}_2\text{O}H2​O and 2 moles O2\text{O}_2O2​ (doubled), or 1 mole H2O2\text{H}_2\text{O}_2H2​O2​ makes 1 mole H2O\text{H}_2\text{O}H2​O and 0.5 moles O2\text{O}_2O2​ (halved)—the 2:2:1 ratio is preserved! In this equation, the mole ratio of H2O\text{H}_2\text{O}H2​O to O2\text{O}_2O2​ is extracted from their coefficients: H2O\text{H}_2\text{O}H2​O has 2 and O2\text{O}_2O2​ has 1 (implied), so it's 2:1, meaning 2 moles of H2O\text{H}_2\text{O}H2​O per 1 mole of O2\text{O}_2O2​. Choice A correctly interprets the coefficients as the mole ratio between H2O\text{H}_2\text{O}H2​O and O2\text{O}_2O2​, stating 2:1. A distractor like choice B (1:2) could result from swapping the order, but always state the ratio as asked—H2O\text{H}_2\text{O}H2​O to O2\text{O}_2O2​ is 2:1, not reversed. Reading mole ratios from balanced equations: (1) Locate the two substances you're comparing in the equation. (2) Read their coefficients (the numbers in front—if no number is written, the coefficient is 1). (3) Write the ratio: [coefficient of first substance] : [coefficient of second substance]. Using mole ratios as conversion factors: mole ratios let you predict amounts! If you know how many moles of one substance you have, you can calculate moles of another using the ratio.

Question 9

Water forms from hydrogen and oxygen as shown in the balanced equation 2H2+O2→2H2O.2\text{H}_2 + \text{O}_2 \rightarrow 2\text{H}_2\text{O}.2H2​+O2​→2H2​O. Which statement correctly describes the mole relationship between O2\text{O}_2O2​ and H2O\text{H}_2\text{O}H2​O?

  1. 1 mol O2\text{O}_2O2​ produces 1 mol H2O\text{H}_2\text{O}H2​O
  2. 2 mol O2\text{O}_2O2​ produces 1 mol H2O\text{H}_2\text{O}H2​O
  3. 1 mol O2\text{O}_2O2​ produces 2 mol H2O\text{H}_2\text{O}H2​O
  4. 2 mol O2\text{O}_2O2​ produces 2 mol H2O\text{H}_2\text{O}H2​O
Explanation: This question tests your understanding that coefficients in balanced chemical equations represent mole ratios—the proportional relationships between amounts of reactants consumed and products formed in a chemical reaction. The coefficients in a balanced equation (the numbers in front of chemical formulas) tell you the ratio of MOLES of each substance involved in the reaction: in 2H2+O2→2H2O2\text{H}_2 + \text{O}_2 \rightarrow 2\text{H}_2\text{O}2H2​+O2​→2H2​O, the coefficients 2, 1, and 2 mean that 222 moles of H2\text{H}_2H2​ react with 111 mole of O2\text{O}_2O2​ to produce 222 moles of H2O\text{H}_2\text{O}H2​O. This ratio is the fundamental relationship—it means for every 111 mole of O2\text{O}_2O2​ consumed, exactly 222 moles of H2\text{H}_2H2​ are consumed and exactly 222 moles of H2O\text{H}_2\text{O}H2​O are produced. The ratio stays constant no matter how much you scale it: 444 moles of H2\text{H}_2H2​ with 222 moles of O2\text{O}_2O2​ makes 444 moles of H2O\text{H}_2\text{O}H2​O (doubled), or 111 mole of H2\text{H}_2H2​ with 0.50.50.5 moles of O2\text{O}_2O2​ makes 111 mole of H2O\text{H}_2\text{O}H2​O (halved)—the 2:1:22:1:22:1:2 ratio is preserved! In this equation, the mole relationship between O2\text{O}_2O2​ and H2O\text{H}_2\text{O}H2​O is that 111 mole of O2\text{O}_2O2​ produces 222 moles of H2O\text{H}_2\text{O}H2​O, as their coefficients are 1 and 2. Choice C correctly interprets the coefficients by stating 1 mol O2\text{O}_2O2​ produces 2 mol H2O\text{H}_2\text{O}H2​O. A distractor like choice A (1 mol O2\text{O}_2O2​ produces 1 mol H2O\text{H}_2\text{O}H2​O) might ignore the coefficients, but remember, the numbers show the proportion—O2\text{O}_2O2​'s 1 to H2O\text{H}_2\text{O}H2​O's 2 means twice as much water is produced. Reading mole ratios from balanced equations: (1) Locate the two substances you're comparing in the equation. (2) Read their coefficients (the numbers in front—if no number is written, the coefficient is 1). (3) Write the ratio: [coefficient of first substance] : [coefficient of second substance]. Using mole ratios as conversion factors: mole ratios let you predict amounts! If you know how many moles of one substance you have, you can calculate moles of another using the ratio.

Question 10

Hydrogen peroxide decomposes as 2H2O2→2H2O+O2.2\text{H}_2\text{O}_2 \rightarrow 2\text{H}_2\text{O} + \text{O}_2.2H2​O2​→2H2​O+O2​. Which statement correctly compares moles of H2O2\text{H}_2\text{O}_2H2​O2​ reacted to moles of O2\text{O}_2O2​ formed?

  1. 2 mol H2O2\text{H}_2\text{O}_2H2​O2​ form 2 mol O2\text{O}_2O2​
  2. 1 mol H2O2\text{H}_2\text{O}_2H2​O2​ forms 2 mol O2\text{O}_2O2​
  3. 2 mol H2O2\text{H}_2\text{O}_2H2​O2​ form 1 mol O2\text{O}_2O2​
  4. 1 mol H2O2\text{H}_2\text{O}_2H2​O2​ forms 1 mol O2\text{O}_2O2​
Explanation: This question tests your understanding that coefficients in balanced chemical equations represent mole ratios—the proportional relationships between amounts of reactants consumed and products formed in a chemical reaction. The coefficients in a balanced equation (the numbers in front of chemical formulas) tell you the ratio of MOLES of each substance involved in the reaction: in 2H₂O₂ → 2H₂O + O₂, the coefficients 2, 2, and 1 mean that 2 moles of hydrogen peroxide decompose to produce 2 moles of water and 1 mole of oxygen. This ratio is the fundamental relationship—it means for every 2 moles of H₂O₂ decomposed, exactly 1 mole of O₂ is produced (along with 2 moles of H₂O). The ratio stays constant no matter how much you scale it: 4 moles H₂O₂ makes 4 moles H₂O and 2 moles O₂ (doubled), or 1 mole H₂O₂ makes 1 mole H₂O and 0.5 moles O₂ (halved)—the 2:2:1 ratio is preserved! In this equation, the comparison of moles of H₂O₂ reacted to moles of O₂ formed is that 2 moles of H₂O₂ form 1 mole of O₂, based on coefficients 2 and 1. Choice C correctly interprets the coefficients by stating 2 mol H₂O₂ form 1 mol O₂. A distractor like choice A (2 mol H₂O₂ form 2 mol O₂) might confuse O₂ with H₂O's coefficient, but O₂ has a 1—always verify the specific substance. Reading mole ratios from balanced equations: (1) Locate the two substances you're comparing in the equation. (2) Read their coefficients (the numbers in front—if no number is written, the coefficient is 1). (3) Write the ratio: [coefficient of first substance] : [coefficient of second substance]. Using mole ratios as conversion factors: mole ratios let you predict amounts! If you know how many moles of one substance you have, you can calculate moles of another using the ratio.