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## Stoichiometry Online MCQs with Answers

In a balanced chemical equation, coefficients represent the __________.
a) Masses of the reactants and products
b) Number of molecules of the reactants and products
c) Volume of the reactants and products
d) Speed of the reaction

b) Number of molecules of the reactants and products

The molar mass of a substance is equal to __________.
a) The atomic mass of the substance
b) The molecular mass of the substance
c) The mass of one mole of the substance
d) The mass of one molecule of the substance

c) The mass of one mole of the substance

The balanced equation for the reaction: 2H2 + O2 → 2H2O represents a __________.
a) Combination reaction
b) Decomposition reaction
c) Displacement reaction
d) Combustion reaction

d) Combustion reaction

The limiting reactant in a chemical reaction is the reactant that __________.
a) Is consumed first
b) Produces the most product
c) Has the highest molar mass
d) Is present in the largest quantity

a) Is consumed first

How many moles of oxygen gas (O2) are needed to react completely with 4 moles of hydrogen gas (H2) in the reaction: 2H2 + O2 → 2H2O?
a) 1 mole
b) 2 moles
c) 3 moles
d) 4 moles

b) 2 moles

The coefficient in a balanced chemical equation represents the __________.
a) Ratio of the masses of the reactants and products
b) Ratio of the volumes of the reactants and products
c) Number of atoms or molecules of the reactants and products
d) Rate of the reaction

c) Number of atoms or molecules of the reactants and products

The molar ratio in a balanced chemical equation is used to __________.
a) Determine the empirical formula of the product
b) Calculate the molecular weight of the product
c) Convert between moles of different substances
d) Determine the solubility of the product

c) Convert between moles of different substances

What is the mole-to-mole ratio of hydrogen gas (H2) to water (H2O) in the reaction: 2H2 + O2 → 2H2O?
a) 1:2
b) 2:1
c) 2:2
d) 1:1

b) 2:1

The stoichiometric coefficient in a balanced chemical equation indicates the __________.
a) Mass of the reactants and products
b) Number of moles of the reactants and products
c) Concentration of the reactants and products
d) Pressure of the reactants and products

b) Number of moles of the reactants and products

How many grams of water (H2O) are produced when 4 moles of hydrogen gas (H2) react with excess oxygen gas (O2) in the reaction: 2H2 + O2 → 2H2O?
a) 18 g
b) 36 g
c) 72 g
d) 144 g

b) 36 g

The percent yield of a chemical reaction is calculated by dividing __________.
a) The actual yield by the theoretical yield and multiplying by 100
b) The theoretical yield by the actual yield and multiplying by 100
c) The actual yield by the mole ratio of the reactants and multiplying by 100
d) The theoretical yield by the stoichiometric coefficient and multiplying by 100

a) The actual yield by the theoretical yield and multiplying by 100

How many moles of aluminum oxide (Al2O3) are produced when 2 moles of aluminum (Al) react with excess oxygen (O2) in the reaction: 4Al + 3O2 → 2Al2O3?
a) 1 mole
b) 2 moles
c) 3 moles
d) 4 moles

a) 1 mole

The stoichiometric coefficient in a balanced chemical equation represents the __________.
a) Mass ratio of the reactants and products
b) Number of molecules of the reactants and products
c) Volume ratio of the reactants and products
d) Rate of the reaction

b) Number of molecules of the reactants and products

How many moles of carbon dioxide (CO2) are produced when 5 moles of propane (C3H8) react with excess oxygen (O2) in the combustion reaction: C3H8 + 5O2 → 3CO2 + 4H2O?
a) 3 moles
b) 4 moles
c) 5 moles
d) 15 moles

a) 3 moles

The stoichiometric coefficient in a balanced chemical equation can be interpreted as the __________.
a) Mass ratio of the reactants and products
b) Number of moles of the reactants and products
c) Volume ratio of the reactants and products
d) Concentration of the reactants and products

b) Number of moles of the reactants and products

How many grams of sulfuric acid (H2SO4) are needed to react completely with 5 moles of magnesium hydroxide (Mg(OH)2) in the reaction: H2SO4 + Mg(OH)2 → MgSO4 + 2H2O?
a) 98 g
b) 196 g
c) 294 g
d) 392 g

c) 294 g

The mole-to-mole ratio of reactants in a balanced chemical equation is used to __________.
a) Determine the limiting reactant
b) Calculate the molar mass of the reactants
c) Convert between grams and moles of the reactants
d) Determine the rate of the reaction

a) Determine the limiting reactant

What is the mole-to-mole ratio of carbon dioxide (CO2) to propane (C3H8) in the combustion reaction: C3H8 + 5O2 → 3CO2 + 4H2O?
a) 3:1
b) 4:3
c) 5:1
d) 1:1

c) 5:1

The actual yield of a chemical reaction is __________.
a) Theoretical yield multiplied by percent yield
b) The amount of product obtained experimentally
c) The maximum possible amount of product
d) The balanced coefficient of the product

b) The amount of product obtained experimentally

How many grams of carbon dioxide (CO2) are produced when 2 moles of methane (CH4) react with excess oxygen (O2) in the combustion reaction: CH4 + 2O2 → CO2 + 2H2O?
a) 22 g
b) 44 g
c) 88 g
d) 176 g

b) 44 g

The stoichiometric coefficient in a balanced chemical equation represents the __________.
a) Mass ratio of the reactants and products
b) Number of moles of the reactants and products
c) Concentration of the reactants and products
d) Rate of the reaction

b) Number of moles of the reactants and products

What is the mole-to-mole ratio of nitrogen gas (N2) to ammonia (NH3) in the reaction: N2 + 3H2 → 2NH3?
a) 1:1
b) 1:2
c) 1:3
d) 2:3

d) 2:3

How many moles of oxygen gas (O2) are needed to react completely with 3 moles of ethane (C2H6) in the combustion reaction: C2H6 + 7O2 → 2CO2 + 3H2O?
a) 7 moles
b) 14 moles
c) 21 moles
d) 42 moles

b) 14 moles

The theoretical yield of a chemical reaction is __________.
a) The actual yield multiplied by the percent yield
b) The amount of product obtained experimentally
c) The maximum possible amount of product
d) The balanced coefficient of the product

c) The maximum possible amount of product

How many grams of potassium chloride (KCl) are produced when 2 moles of potassium (K) react with excess chlorine gas (Cl2) in the reaction: 2K + Cl2 → 2KCl?
a) 74.55 g
b) 118.17 g
c) 148.04 g
d) 296.08 g

b) 118.17 g

The stoichiometric coefficient in a balanced chemical equation represents the __________.
a) Mass ratio of the reactants and products
b) Number of molecules of the reactants and products
c) Volume ratio of the reactants and products
d) Rate of the reaction

b) Number of molecules of the reactants and products

What is the mole-to-mole ratio of hydrogen gas (H2) to water (H2O) in the reaction: 2H2 + O2 → 2H2O?
a) 1:1
b) 2:1
c) 2:2
d) 1:2

b) 2:1

How many moles of aluminum oxide (Al2O3) are produced when 4 moles of aluminum (Al) react with excess oxygen (O2) in the reaction: 4Al + 3O2 → 2Al2O3?
a) 2 moles
b) 4 moles
c) 6 moles
d) 8 moles

a) 2 moles

The balanced equation for the reaction: 2H2 + O2 → 2H2O represents a __________.
a) Combination reaction
b) Decomposition reaction
c) Displacement reaction
d) Combustion reaction

d) Combustion reaction

The mole-to-mole ratio of reactants in a balanced chemical equation is used to __________.
a) Determine the limiting reactant
b) Calculate the molar mass of the reactants
c) Convert between grams and moles of the reactants
d) Determine the rate of the reaction

a) Determine the limiting reactant

What is the mole-to-mole ratio of carbon dioxide (CO2) to propane (C3H8) in the combustion reaction: C3H8 + 5O2 → 3CO2 + 4H2O?
a) 3:1
b) 4:3
c) 5:1
d) 1:1

c) 5:1

The limiting reactant in a chemical reaction is the reactant that __________.
a) Is consumed first
b) Produces the most product
c) Has the highest molar mass
d) Is present in the largest quantity

a) Is consumed first

How many moles of oxygen gas (O2) are needed to react completely with 5 moles of hydrogen gas (H2) in the reaction: 2H2 + O2 → 2H2O?
a) 1 mole
b) 2 moles
c) 3 moles
d) 4 moles

b) 2 moles

The coefficient in a balanced chemical equation represents the __________.
a) Ratio of the masses of the reactants and products
b) Ratio of the volumes of the reactants and products
c) Number of atoms or molecules of the reactants and products
d) Rate of the reaction

c) Number of atoms or molecules of the reactants and products

How many grams of water (H2O) are produced when 4 moles of hydrogen gas (H2) react with excess oxygen gas (O2) in the reaction: 2H2 + O2 → 2H2O?
a) 18 g
b) 36 g
c) 72 g
d) 144 g

b) 36 g

The molar mass of a substance is equal to __________.
a) The atomic mass of the substance
b) The molecular mass of the substance
c) The mass of one mole of the substance
d) The mass of one molecule of the substance

c) The mass of one mole of the substance

The stoichiometric coefficient in a balanced chemical equation indicates the __________.
a) Mass of the reactants and products
b) Number of moles of the reactants and products
c) Concentration of the reactants and products
d) Pressure of the reactants and products

b) Number of moles of the reactants and products

How many moles of carbon dioxide (CO2) are produced when 5 moles of propane (C3H8) react with excess oxygen (O2) in the combustion reaction: C3H8 + 5O2 → 3CO2 + 4H2O?
a) 3 moles
b) 4 moles
c) 5 moles
d) 15 moles

a) 3 moles

The molar ratio in a balanced chemical equation is used to __________.
a) Determine the empirical formula of the product
b) Calculate the molecular weight of the product
c) Convert between moles of different substances
d) Determine the solubility of the product

c) Convert between moles of different substances

How many moles of sulfuric acid (H2SO4) are needed to react completely with 5 moles of magnesium hydroxide (Mg(OH)2) in the reaction: H2SO4 + Mg(OH)2 → MgSO4 + 2H2O?
a) 5 moles
b) 10 moles
c) 15 moles
d) 20 moles

c) 15 moles

The percent yield of a chemical reaction is calculated by dividing __________.
a) The actual yield by the theoretical yield and multiplying by 100
b) The theoretical yield by the actual yield and multiplying by 100
c) The actual yield by the mole ratio of the reactants and multiplying by 100
d) The theoretical yield by the stoichiometric coefficient and multiplying by 100

a) The actual yield by the theoretical yield and multiplying by 100

How many grams of nitrogen gas (N2) are produced when 2 moles of ammonia (NH3) decompose in the reaction: 2NH3 → N2 + 3H2?
a) 28 g
b) 32 g
c) 40 g
d) 56 g

d) 56 g

The stoichiometric coefficient in a balanced chemical equation represents the __________.
a) Mass ratio of the reactants and products
b) Number of moles of the reactants and products
c) Volume ratio of the reactants and products
d) Concentration of the reactants and products

b) Number of moles of the reactants and products

How many moles of oxygen gas (O2) are needed to react completely with 3 moles of ethane (C2H6) in the combustion reaction: C2H6 + 7O2 → 2CO2 + 3H2O?
a) 3 moles
b) 6 moles
c) 9 moles
d) 21 moles

b) 6 moles

The stoichiometric coefficient in a balanced chemical equation can be interpreted as the __________.
a) Mass ratio of the reactants and products
b) Number of moles of the reactants and products
c) Volume ratio of the reactants and products
d) Concentration of the reactants and products

b) Number of moles of the reactants and products

How many grams of sulfuric acid (H2SO4) are needed to react completely with 2 moles of sodium hydroxide (NaOH) in the reaction: H2SO4 + 2NaOH → Na2SO4 + 2H2O?
a) 98 g
b) 196 g
c) 294 g
d) 392 g

b) 196 g

The mole-to-mole ratio of reactants in a balanced chemical equation is used to __________.
a) Determine the limiting reactant
b) Calculate the molar mass of the reactants
c) Convert between grams and moles of the reactants
d) Determine the rate of the reaction

a) Determine the limiting reactant

What is the mole-to-mole ratio of nitrogen gas (N2) to ammonia (NH3) in the reaction: N2 + 3H2 → 2NH3?
a) 1:1
b) 1:2
c) 1:3
d) 2:3

d) 2:3

How many moles of oxygen gas (O2) are needed to react completely with 4 moles of hydrogen gas (H2) in the reaction: 2H2 + O2 → 2H2O?
a) 2 moles
b) 4 moles
c) 6 moles
d) 8 moles

c) 6 moles

The actual yield of a chemical reaction is __________.
a) Theoretical yield multiplied by percent yield
b) The amount of product obtained experimentally
c) The maximum possible amount of product
d) The balanced coefficient of the product

b) The amount of product obtained experimentally

How many grams of potassium chloride (KCl) are produced when 2 moles of potassium (K) react with excess chlorine gas (Cl2) in the reaction: 2K + Cl2 → 2KCl?
a) 74.55 g
b) 118.17 g
c) 148.04 g
d) 296.08 g

b) 118.17 g

The theoretical yield of a chemical reaction is __________.
a) The actual yield multiplied by the percent yield
b) The amount of product obtained experimentally
c) The maximum possible amount of product
d) The balanced coefficient of the product

c) The maximum possible amount of product

How many grams of water (H2O) are produced when 3 moles of hydrogen gas (H2) react with excess oxygen gas (O2) in the reaction: 2H2 + O2 → 2H2O?
a) 18 g
b) 36 g
c) 54 g
d) 72 g

c) 54 g

The mole-to-mole ratio of carbon dioxide (CO2) to propane (C3H8) in the combustion reaction: C3H8 + 5O2 → 3CO2 + 4H2O is __________.
a) 3:1
b) 4:3
c) 5:1
d) 1:1

c) 5:1

How many moles of oxygen gas (O2) are needed to react completely with 2 moles of carbon monoxide (CO) in the reaction: 2CO + O2 → 2CO2?
a) 1 mole
b) 2 moles
c) 3 moles
d) 4 moles

b) 2 moles

The stoichiometric coefficient in a balanced chemical equation represents the __________.
a) Mass ratio of the reactants and products
b) Number of moles of the reactants and products
c) Volume ratio of the reactants and products
d) Concentration of the reactants and products

b) Number of moles of the reactants and products

How many grams of sulfuric acid (H2SO4) are needed to react completely with 3 moles of potassium hydroxide (KOH) in the reaction: H2SO4 + 2KOH → K2SO4 + 2H2O?
a) 98 g
b) 196 g
c) 294 g
d) 392 g

c) 294 g

The mole-to-mole ratio of reactants in a balanced chemical equation is used to __________.
a) Determine the limiting reactant
b) Calculate the molar mass of the reactants
c) Convert between grams and moles of the reactants
d) Determine the rate of the reaction

a) Determine the limiting reactant

What is the mole-to-mole ratio of hydrogen gas (H2) to water (H2O) in the reaction: 2H2 + O2 → 2H2O?
a) 1:1
b) 2:1
c) 2:2
d) 1:2

b) 2:1

How many moles of oxygen gas (O2) are needed to react completely with 6 moles of ethane (C2H6) in the combustion reaction: C2H6 + 7O2 → 2CO2 + 3H2O?
a) 6 moles
b) 12 moles
c) 18 moles
d) 42 moles

d) 42 moles

The balanced equation for the reaction: 2H2 + O2 → 2H2O represents a __________.
a) Combination reaction
b) Decomposition reaction
c) Displacement reaction
d) Combustion reaction

d) Combustion reaction

How many grams of carbon dioxide (CO2) are produced when 2 moles of glucose (C6H12O6) are burned in the reaction: C6H12O6 + 6O2 → 6CO2 + 6H2O?
a) 88 g
b) 176 g
c) 264 g
d) 352 g

b) 176 g

The stoichiometric coefficient in a balanced chemical equation can be interpreted as the __________.
a) Mass ratio of the reactants and products
b) Number of molecules of the reactants and products
c) Volume ratio of the reactants and products
d) Concentration of the reactants and products

b) Number of molecules of the reactants and products

How many moles of oxygen gas (O2) are needed to react completely with 4 moles of methane (CH4) in the combustion reaction: CH4 + 2O2 → CO2 + 2H2O?
a) 4 moles
b) 8 moles
c) 12 moles
d) 16 moles

c) 12 moles

The molar mass of a substance is equal to __________.
a) The atomic mass of the substance
b) The molecular mass of the substance
c) The mass of one mole of the substance
d) The mass of one molecule of the substance

c) The mass of one mole of the substance

What is the mole-to-mole ratio of carbon dioxide (CO2) to oxygen gas (O2) in the combustion reaction: C3H8 + 5O2 → 3CO2 + 4H2O?
a) 3:5
b) 3:4
c) 5:3
d) 4:3

d) 4:3

How many grams of sodium chloride (NaCl) are produced when 2 moles of sodium (Na) react with excess chlorine gas (Cl2) in the reaction: 2Na + Cl2 → 2NaCl?
a) 58.44 g
b) 116.88 g
c) 174.66 g
d) 349.32 g

b) 116.88 g

The stoichiometric coefficient in a balanced chemical equation represents the __________.
a) Mass ratio of the reactants and products
b) Number of atoms or molecules of the reactants and products
c) Volume ratio of the reactants and products
d) Rate of the reaction

b) Number of atoms or molecules of the reactants and products

How many moles of hydrogen gas (H2) are needed to react completely with 3 moles of nitrogen gas (N2) in the reaction: N2 + 3H2 → 2NH3?
a) 1 mole
b) 2 moles
c) 3 moles
d) 6 moles