stoichiometry federal

Practice Stoichiometry MCQs designed for Federal Board students. Enhance your problem-solving skills with topic-specific questions and detailed explanations.

Mole, molar volume, molar mass, and the density of gases

1. What is defined as one mole of any substance?

• A) 6.02 x 10²³ molecules
• B) The mass of an atom
• C) One liter of a gas at STP
• D) One gram of a substance
• Answer: A) 6.02 x 10²³ molecules

1. The molar mass of a substance is:

• A) The volume of one mole of gas at STP
• B) The mass of one mole of a substance
• C) The number of moles per liter
• D) The density of the substance
• Answer: B) The mass of one mole of a substance

1. What is the molar volume of an ideal gas at STP?

• A) 22.4 L
• B) 6.02 L
• C) 1.00 L
• D) 44.8 L
• Answer: A) 22.4 L

1. Which statement best defines Avogadro’s number?

• A) The volume occupied by 1 mole of any gas at STP
• B) The number of atoms in 12 g of carbon-12
• C) The atomic mass of any element
• D) The molar mass of a substance
• Answer: B) The number of atoms in 12 g of carbon-12

1. The density of a gas at STP can be calculated using:

• A) Density = molar mass / molar volume
• B) Density = molar mass x volume
• C) Density = moles x temperature
• D) Density = molar mass / pressure
• Answer: A) Density = molar mass / molar volume

1. If a gas has a molar mass of 44 g/mol, its density at STP would be:

• A) 0.5 g/L
• B) 1.96 g/L
• C) 2.5 g/L
• D) 44 g/L
• Answer: B) 1.96 g/L

1. Which gas law explains the relationship between molar volume and temperature?

• A) Boyle’s Law
• B) Charles’s Law
• C) Avogadro’s Law
• D) Ideal Gas Law
• Answer: B) Charles’s Law

1. At STP, which of the following gases will have the greatest density?

• A) ( \text{H}_2 )
• B) ( \text{O}_2 )
• C) ( \text{CO}_2 )
• D) ( \text{He} )
• Answer: C) ( \text{CO}_2 )

1. One mole of ( \text{H}_2 ) gas at STP occupies:

• A) 11.2 L
• B) 22.4 L
• C) 33.6 L
• D) 44.8 L
• Answer: B) 22.4 L

1. The mass of 1 mole of ( \text{CO}_2 ) is approximately:
   • A) 28 g
   • B) 32 g
   • C) 44 g
   • D) 16 g
   • Answer: C) 44 g
2. Which term describes the mass of one mole of any chemical element or compound?
   • A) Molecular weight
   • B) Molar volume
   • C) Atomic mass
   • D) Molar mass
   • Answer: D) Molar mass
3. If a gas has a molar mass of 2 g/mol, what would be its density at STP?
   • A) 0.089 g/L
   • B) 0.178 g/L
   • C) 0.5 g/L
   • D) 2 g/L
   • Answer: B) 0.178 g/L
4. The molar mass of ( \text{O}_2 ) is:
   • A) 16 g/mol
   • B) 32 g/mol
   • C) 8 g/mol
   • D) 48 g/mol
   • Answer: B) 32 g/mol
5. At constant temperature and pressure, the volume of gas is directly proportional to:
   • A) Mass
   • B) Molar mass
   • C) Number of moles
   • D) Density
   • Answer: C) Number of moles
6. What is the volume occupied by 0.5 moles of a gas at STP?
   • A) 11.2 L
   • B) 22.4 L
   • C) 5.6 L
   • D) 44.8 L
   • Answer: A) 11.2 L
7. The density of a gas at STP depends on:
   • A) Temperature
   • B) Molar mass
   • C) Volume
   • D) Avogadro’s number
   • Answer: B) Molar mass
8. Which unit is used to measure molar volume of a gas?
   • A) g/mol
   • B) mol/L
   • C) L/mol
   • D) mol/g
   • Answer: C) L/mol
9. For a given gas, doubling the pressure at constant temperature will:
   • A) Double the volume
   • B) Halve the volume
   • C) Keep the volume constant
   • D) Double the density
   • Answer: B) Halve the volume
10. Which of the following represents the correct molar volume of a gas at STP?
    • A) 11.2 L/mol
    • B) 22.4 L/mol
    • C) 33.6 L/mol
    • D) 44.8 L/mol
    • Answer: B) 22.4 L/mol
11. How many moles are present in 44.8 L of ( \text{CO}_2 ) gas at STP?
    • A) 1 mole
    • B) 2 moles
    • C) 0.5 moles
    • D) 3 moles
    • Answer: B) 2 moles
12. If the molar mass of a gas is known, its density at STP can be calculated by:
    • A) Dividing molar mass by Avogadro’s number
    • B) Dividing molar mass by molar volume
    • C) Multiplying molar mass by volume
    • D) Dividing molar mass by temperature
    • Answer: B) Dividing molar mass by molar volume
13. The mass of 1 mole of ( \text{N}_2 ) gas is:
    • A) 14 g
    • B) 28 g
    • C) 2 g
    • D) 32 g
    • Answer: B) 28 g
14. Which of the following represents Avogadro’s law?
    • A) ( P \propto V )
    • B) ( V \propto T )
    • C) ( V \propto n )
    • D) ( P \propto T )
    • Answer: C) ( V \propto n )
15. The density of ( \text{O}_2 ) gas at STP is approximately:
    • A) 1.43 g/L
    • B) 0.5 g/L
    • C) 2.86 g/L
    • D) 1.2 g/L
    • Answer: A) 1.43 g/L
16. What volume will 1 mole of ( \text{CH}_4 ) gas occupy at STP?
    • A) 44.8 L
    • B) 22.4 L
    • C) 11.2 L
    • D) 5.6 L
    • Answer: B) 22.4 L

Stoichiometric calculations, mole ratios, and mole-mole calculations

1. In a balanced chemical equation, the coefficients represent the:

• A) Mass ratio of reactants and products
• B) Mole ratio of reactants and products
• C) Volume ratio at STP
• D) Molecular weights
• Answer: B) Mole ratio of reactants and products

1. What is the mole ratio of H₂ to O₂ in the reaction 2H₂ + O₂ → 2H₂O?

• A) 1:1
• B) 2:1
• C) 1:2
• D) 3:2
• Answer: B) 2:1

1. In the equation N₂ + 3H₂ → 2NH₃ , how many moles of NH₃ are produced from 6 moles of H₂ ?

• A) 1 mole
• B) 2 moles
• C) 3 moles
• D) 4 moles
• Answer: C) 3 moles

1. What is the first step in solving stoichiometric problems?

• A) Calculating the molar mass
• B) Balancing the chemical equation
• C) Converting grams to moles
• D) Determining the limiting reagent
• Answer: B) Balancing the chemical equation

1. In a chemical reaction, the mole ratio between two reactants can be determined from:

• A) Their atomic masses
• B) The coefficients in the balanced equation
• C) Their physical states
• D) The reaction rate
• Answer: B) The coefficients in the balanced equation

1. Using the balanced equation 4Fe + 3O₂ → 2Fe₂O₃ , how many moles of Fe₂O₃ ) will form from 4 moles of Fe?

• A) 1 mole
• B) 2 moles
• C) 3 moles
• D) 4 moles
• Answer: B) 2 moles

1. In the reaction ( 2KClO₃ → 2KCl + 3O₂ ), how many moles of O₂ ) are produced from 4 moles of KClO₃ )?

• A) 2 moles
• B) 3 moles
• C) 4 moles
• D) 6 moles
• Answer: D) 6 moles

1. If 2 moles of H₂ react with O₂ to form water, what is the mole ratio of H₂ to H₂O?

• A) 1:1
• B) 1:2
• C) 2:2
• D) 2:1
• Answer: A) 1:1

1. In a reaction, if the mole ratio between reactant A and product B is 1:3, then 2 moles of A will produce how many moles of B?

• A) 1 mole
• B) 2 moles
• C) 3 moles
• D) 6 moles
• Answer: D) 6 moles

1. The stoichiometric coefficient indicates:
   • A) The mass of each reactant and product
   • B) The energy released in the reaction
   • C) The number of moles involved in the reaction
   • D) The color of the compounds
   • Answer: C) The number of moles involved in the reaction
2. In a combustion reaction, if the mole ratio of CH₄ to O₂ is 1:2, how many moles of O₂ are required to completely burn 5 moles of CH₄ ?
   • A) 2.5 moles
   • B) 5 moles
   • C) 10 moles
   • D) 15 moles
   • Answer: C) 10 moles
3. Using the equation 2SO₂ + O₂ → 2SO₃, if 2 moles of SO₂ react, how many moles of SO₃ will be formed?
   • A) 1 mole
   • B) 2 moles
   • C) 3 moles
   • D) 4 moles
   • Answer: B) 2 moles
4. How many moles of HCl are needed to react completely with 1 mole of NaOH in the reaction HCl + NaOH → NaCl + H₂O?
   • A) 0.5 moles
   • B) 1 mole
   • C) 1.5 moles
   • D) 2 moles
   • Answer: B) 1 mole
5. In the reaction ( 3H2 + N2 → 2NH3, the mole ratio of N2 to NH3 is:
   • A) 1:1
   • B) 1:2
   • C) 2:3
   • D) 3:1
   • Answer: B) 1:2
6. What is the mole ratio of CO2 ) to C2H4 ) in the complete combustion reaction C2H4 + 3O2→ 2CO2 + 2H2O?
   • A) 1:2
   • B) 2:1
   • C) 1:1
   • D) 3:2
   • Answer: B) 2:1
7. The mole ratio of O₂ + CO₂ in the reaction CH₄ + 2O₂ → CO₂ + 2H₂O is:
   • A) 1:1
   • B) 1:2
   • C) 2:1
   • D) 2:3
   • Answer: A) 1:1
8. In the balanced equation C₆H₁₂O₆ → 2C₂H₅OH + 2CO₂ , how many moles of CO₂ are produced from 1 mole of C₆H₁₂O₆ ?
   • A) 1 mole
   • B) 2 moles
   • C) 3 moles
   • D) 4 moles
   • Answer: B) 2 moles
9. The equation 2Mg + O₂ → 2MgO indicates that 4 moles of Mg will react with how many moles of O₂ ?
   • A) 1 mole
   • B) 2 moles
   • C) 3 moles
   • D) 4 moles
   • Answer: B) 2 mole

20. In the reaction H₂ + Cl₂ → 2HCl, the mole ratio of H₂ to HCl is:
    • A) 1:1
    • B) 1:2
    • C) 2:1
    • D) 2:2
    • Answer: B) 1:2

Solution Stoichiometry

1. What is solution stoichiometry used for?

• A) To find gas pressure
• B) To calculate solute amount in a solution
• C) To determine atomic mass
• D) To measure density
• Answer: B) To calculate solute amount in a solution

1. In solution stoichiometry, molarity (M) is defined as:

• A) Moles of solute per liter of solution
• B) Moles of solvent per liter of solution
• C) Grams per liter
• D) Moles per kilogram
• Answer: A) Moles of solute per liter of solution

1. If 2 moles of NaCl are dissolved in 1 L of water, what is the molarity?

• A) 1 M
• B) 2 M
• C) 0.5 M
• D) 4 M
• Answer: B) 2 M

1. The unit of molarity is:

• A) mol/g
• B) mol/L
• C) L/mol
• D) g/mol
• Answer: B) mol/L

1. To dilute a solution, you would:

• A) Add more solute
• B) Increase temperature
• C) Add more solvent
• D) Remove solvent
• Answer: C) Add more solvent

1. In the equation ( \text{M}_1\text{V}_1 = \text{M}_2\text{V}_2 ), ( \text{M}_2 ) represents:

• A) Final molarity
• B) Initial volume
• C) Final mass
• D) Initial molarity
• Answer: A) Final molarity

1. What is the molarity of a solution with 0.5 moles of KCl in 0.25 L?

• A) 1 M
• B) 2 M
• C) 0.25 M
• D) 0.5 M
• Answer: B) 2 M

1. If you mix equal volumes of 1 M HCl and 1 M NaOH, the resulting solution is:

• A) Acidic
• B) Neutral
• C) Basic
• D) Salty
• Answer: B) Neutral

1. To prepare 1 L of 1 M NaOH, you need:

• A) 1 g NaOH
• B) 10 g NaOH
• C) 40 g NaOH
• D) 0.1 g NaOH
• Answer: C) 40 g NaOH

1. If you dilute 1 L of 2 M solution to 2 L, the new molarity is:
   • A) 4 M
   • B) 2 M
   • C) 1 M
   • D) 0.5 M
   • Answer: C) 1 M
2. The molarity of a solution with 3 moles of solute in 3 L is:
   • A) 0.5 M
   • B) 1 M
   • C) 2 M
   • D) 3 M
   • Answer: B) 1 M
3. What volume of 0.5 M H₂SO₄ is needed for 0.25 moles of H₂SO₄ ?
   • A) 0.5 L
   • B) 0.25 L
   • C) 1 L
   • D) 0.75 L
   • Answer: A) 0.5 L
4. If 0.2 L of 1 M NaCl is diluted to 1 L, the molarity becomes:
   • A) 0.2 M
   • B) 0.5 M
   • C) 1 M
   • D) 0.1 M
   • Answer: D) 0.1 M
5. How many moles are in 250 mL of 2 M HCl?
   • A) 0.25 mol
   • B) 0.5 mol
   • C) 1 mol
   • D) 2 mol
   • Answer: B) 0.5 mol
6. The equation M1V1 = M2V2 is used for:
   • A) Dilution calculations
   • B) Gas laws
   • C) Solid solubility
   • D) Stoichiometry only
   • Answer: A) Dilution calculations
7. How many liters of 1 M solution contain 2 moles of solute?
   • A) 0.5 L
   • B) 1 L
   • C) 2 L
   • D) 3 L
   • Answer: C) 2 L
8. In solution stoichiometry, molarity is used to calculate:
   • A) Mass of a gas
   • B) Volume of solution
   • C) Concentration of solution
   • D) Density
   • Answer: C) Concentration of solution
9. How many moles are present in 0.5 L of a 1 M solution?
   • A) 1 mole
   • B) 0.5 mole
   • C) 0.25 mole
   • D) 2 moles
   • Answer: B) 0.5 mole
10. To dilute a 2 M solution to 1 M, you need to:
    • A) Add twice the amount of solvent
    • B) Remove half the solute
    • C) Add solute
    • D) Heat the solution
    • Answer: A) Add twice the amount of solvent
11. A 1 M solution of HCl contains:
    • A) 1 mole of HCl in 1 L of solution
    • B) 1 gram of HCl in 1 L
    • C) 2 moles of HCl
    • D) 1 mole of HCl in 100 mL
    • Answer: A) 1 mole of HCl in 1 L of solution

Limiting and non-limiting reactants:

1. What is a limiting reactant?

• A) The reactant that is completely used up
• B) The reactant in excess
• C) The product formed
• D) The reactant that remains
• Answer: A) The reactant that is completely used up

1. What is a non-limiting reactant?

• A) Reactant completely used up
• B) Reactant that is left over
• C) Reactant that forms no product
• D) Product formed
• Answer: B) Reactant that is left over

1. In a reaction, the limiting reactant determines:

• A) Only the products
• B) The amount of product formed
• C) Reaction rate
• D) The final color of the solution
• Answer: B) The amount of product formed

1. If all of a reactant is used up, it is:

• A) Excess reactant
• B) Limiting reactant
• C) Product
• D) Catalyst
• Answer: B) Limiting reactant

1. Which reactant is in excess?

• A) Reactant fully consumed
• B) Reactant partially left over
• C) Reactant that forms the most product
• D) Product formed in a reaction
• Answer: B) Reactant partially left over

1. How is the limiting reactant identified?

• A) By mass alone
• B) By comparing moles needed vs. moles available
• C) By color of solution
• D) By boiling point
• Answer: B) By comparing moles needed vs. moles available

1. What happens to the excess reactant?

• A) It forms all products
• B) It remains after the reaction
• C) It becomes limiting
• D) It is used first
• Answer: B) It remains after the reaction

1. Why is the limiting reactant important?

• A) Determines reaction color
• B) Limits amount of product
• C) Increases temperature
• D) Changes reaction rate
• Answer: B) Limits amount of product

1. In the reaction 2H₂ + O₂ → 2H₂O, if (O₂) is limited, which is in excess?

• A) H₂
• B) H₂O
• C) O₂
• D) All are limiting
• Answer: A) H₂

1. To find the limiting reactant, you must know:
   • A) Molar masses of products
   • B) Mole ratios from the balanced equation
   • C) Initial pressure of gases
   • D) Density of products
   • Answer: B) Mole ratios from the balanced equation

Theoretical yield, actual yield, and percent yield:

1. What is the theoretical yield?

• A) Actual product formed
• B) Maximum product possible
• C) Excess reactant remaining
• D) Minimum product possible
• Answer: B) Maximum product possible

1. What is the actual yield?

• A) Maximum yield calculated
• B) Yield obtained in the lab
• C) Theoretical prediction
• D) Half of the expected yield
• Answer: B) Yield obtained in the lab

1. Percent yield is calculated as:

• A) (Theoretical yield / Actual yield) x 100
• B) (Actual yield / Theoretical yield) x 100
• C) Actual yield + Theoretical yield
• D) (Theoretical yield – Actual yield) x 100
• Answer: B) (Actual yield / Theoretical yield) x 100

1. If the actual yield is equal to the theoretical yield, percent yield is:

• A) 50%
• B) 100%
• C) 0%
• D) 200%
• Answer: B) 100%

1. A reaction’s theoretical yield depends on:

• A) Limiting reactant
• B) Excess reactant
• C) Density
• D) Product color
• Answer: A) Limiting reactant

1. Which yield is usually lower due to loss in experiments?

• A) Theoretical yield
• B) Actual yield
• C) Percent yield
• D) Limiting yield
• Answer: B) Actual yield

1. If theoretical yield is 10g and actual yield is 7g, percent yield is:

• A) 70%
• B) 140%
• C) 30%
• D) 10%
• Answer: A) 70%

1. Percent yield above 100% indicates:

• A) No product was formed
• B) Calculation error or impurities
• C) Perfect reaction efficiency
• D) Theoretical yield exceeded
• Answer: B) Calculation error or impurities

1. A low percent yield could indicate:

• A) Very high efficiency
• B) Loss of product during reaction
• C) Overestimation of reactants
• D) Increase in reactant mass
• Answer: B) Loss of product during reaction

1. Percent yield is useful to:
   • A) Measure reactant purity
   • B) Assess reaction efficiency
   • C) Calculate reaction color
   • D) Determine reaction temperature
   • Answer: B) Assess reaction efficiency

Importance of stoichiometry in the production and dosage of medicines:

1. Stoichiometry helps in calculating:

• A) Dosage accuracy
• B) Medicine color
• C) Taste of drugs
• D) Shelf life
• Answer: A) Dosage accuracy

1. Why is stoichiometry important in medicine production?

• A) To increase weight
• B) For precise formulation
• C) To reduce side effects
• D) For color consistency
• Answer: B) For precise formulation

1. In drug formulation, stoichiometry ensures:

• A) Stability of medicine
• B) Accurate active ingredient amount
• C) Reduced cost
• D) Faster production
• Answer: B) Accurate active ingredient amount

1. Incorrect stoichiometric calculations can lead to:

• A) Reduced potency
• B) Exact dosage
• C) Increased potency
• D) Only taste change
• Answer: A) Reduced potency

1. Which concept is essential for determining the correct medicine dose?

• A) Stoichiometry
• B) Color theory
• C) Surface tension
• D) Filtration
• Answer: A) Stoichiometry

1. Stoichiometry helps in avoiding:

• A) Medicine overdose
• B) Improved packaging
• C) Medicine odor
• D) None of the above
• Answer: A) Medicine overdose

1. In pharmaceutical production, stoichiometry ensures:

• A) Standardized drug potency
• B) Different potency in each batch
• C) Faster reaction times
• D) Reduced reactivity
• Answer: A) Standardized drug potency

1. Accurate stoichiometric calculations in medicine are crucial for:

• A) Patient safety
• B) Reducing cost
• C) Enhancing color
• D) Speeding up reactions
• Answer: A) Patient safety

1. Using stoichiometry in medicine dosage prevents:

• A) Side effects from wrong dosages
• B) Faster dissolution
• C) Taste change
• D) Medicine discoloration
• Answer: A) Side effects from wrong dosages

1. Proper stoichiometric ratios in drugs affect:
   • A) Effectiveness and safety
   • B) Flavor of medicine
   • C) Cost of production
   • D) Packaging quality
   • Answer: A) Effectiveness and safety