Molar mass of H2SO4 = 2 + 32 + 16*4 = 98 g/mol. Number of moles = 200 g / 98 g/mol = 2.04 moles.
Correct Answer: B — 2
Q. How many moles are in 5.6 liters of a gas at STP?
A.0.25
B.0.5
C.1
D.2
Solution
At STP, 1 mole of gas occupies 22.4 L. Number of moles = volume / molar volume = 5.6 L / 22.4 L/mole = 0.25 moles.
Correct Answer: C — 1
Q. How many moles are in 5.6 liters of an ideal gas at STP?
A.0.25
B.0.5
C.1
D.2
Solution
At STP, 1 mole of gas occupies 22.4 L. Therefore, number of moles = 5.6 L / 22.4 L/mole = 0.25 moles.
Correct Answer: B — 0.5
Q. How many moles are in 50 grams of H2O?
A.2.78
B.1.39
C.0.56
D.3.06
Solution
Molar mass of H2O = 2*1 + 16 = 18 g/mol. Number of moles = mass/molar mass = 50 g / 18 g/mol = 2.78 moles.
Correct Answer: B — 1.39
Q. How many moles are in 500 mL of a 2 M NaCl solution?
A.0.5
B.1
C.2
D.4
Solution
Moles = molarity x volume (in L) = 2 M x 0.5 L = 1 mole.
Correct Answer: B — 1
Q. How many moles are in 88 grams of O2?
A.1
B.2
C.3
D.4
Solution
Molar mass of O2 = 16*2 = 32 g/mol. Number of moles = mass/molar mass = 88 g / 32 g/mol = 2.75 moles.
Correct Answer: B — 2
Q. How many moles of KCl are produced when 2 moles of K react with 2 moles of Cl2?
A.1 mole
B.2 moles
C.3 moles
D.4 moles
Solution
The balanced equation is 2K + Cl2 → 2KCl. Therefore, 2 moles of K will produce 2 moles of KCl.
Correct Answer: B — 2 moles
Q. How many moles of oxygen are required to completely react with 4 moles of ethane (C2H6)?
A.5 moles
B.7 moles
C.8 moles
D.10 moles
Solution
The balanced equation is 2C2H6 + 7O2 → 4CO2 + 6H2O. Therefore, 4 moles of C2H6 require 14 moles of O2, which means 7 moles of O2 for 2 moles of C2H6.
Correct Answer: B — 7 moles
Q. If 0.5 moles of a gas occupy 11.2 liters at STP, what is the molar volume of the gas?
A.22.4 L
B.11.2 L
C.5.6 L
D.44.8 L
Solution
At STP, 1 mole of gas occupies 22.4 L. Therefore, the molar volume is 22.4 L.
Correct Answer: A — 22.4 L
Q. If 0.5 moles of NaCl are dissolved in 1 liter of water, what is the concentration of NaCl in the solution?
A.0.5 M
B.1 M
C.2 M
D.0.25 M
Solution
Concentration (M) = moles of solute / liters of solution = 0.5 moles / 1 L = 0.5 M.
Correct Answer: A — 0.5 M
Q. If 0.5 moles of NaCl are dissolved in 1 liter of water, what is the concentration of NaCl?
A.0.5 M
B.1 M
C.2 M
D.0.25 M
Solution
Concentration (M) = moles of solute / liters of solution = 0.5 moles / 1 L = 0.5 M.
Correct Answer: A — 0.5 M
Q. If 0.5 moles of NaCl are dissolved in 1 liter of water, what is the molarity of the solution?
A.0.5 M
B.1 M
C.2 M
D.0.25 M
Solution
Molarity (M) = moles of solute / liters of solution = 0.5 moles / 1 L = 0.5 M.
Correct Answer: A — 0.5 M
Q. If 1 L of a 2 M solution is diluted to 3 L, what is the new molarity of the solution?
A.0.67 M
B.1 M
C.1.5 M
D.2 M
Solution
Using the dilution formula M1V1 = M2V2, we have 2 M * 1 L = M2 * 3 L, thus M2 = 2/3 = 0.67 M.
Correct Answer: A — 0.67 M
Q. If 1 L of a 3 M solution is diluted to 2 L, what is the new molarity?
A.1.5 M
B.3 M
C.6 M
D.0.5 M
Solution
Using the dilution formula M1V1 = M2V2, we have 3 M × 1 L = M2 × 2 L. Thus, M2 = 1.5 M.
Correct Answer: A — 1.5 M
Q. If 1 mol of NaCl is dissolved in 1 kg of water, how many particles are present in solution?
A.1
B.2
C.3
D.4
Solution
NaCl dissociates into 2 ions (Na+ and Cl-), so 1 mol of NaCl produces 2 mol of particles in solution.
Correct Answer: B — 2
Q. If 1 mol of NaCl is dissolved in 1 kg of water, what is the expected van 't Hoff factor (i)?
A.1
B.2
C.3
D.4
Solution
NaCl dissociates into 2 ions (Na+ and Cl-), so the van 't Hoff factor i = 2.
Correct Answer: B — 2
Q. If 1 mole of a gas occupies 22.4 L at STP, how much volume will 0.5 moles occupy?
A.11.2 L
B.22.4 L
C.44.8 L
D.5.6 L
Solution
Volume = moles x volume per mole = 0.5 moles x 22.4 L/mole = 11.2 L.
Correct Answer: A — 11.2 L
Q. If 1 mole of a non-electrolyte solute is dissolved in 1 kg of water, what is the expected freezing point depression?
A.-1.86 °C
B.-3.72 °C
C.-0.52 °C
D.-2.00 °C
Solution
The freezing point depression is calculated using the formula ΔTf = Kf * m, where Kf for water is 1.86 °C kg/mol.
Correct Answer: A — -1.86 °C
Q. If 1 mole of a non-electrolyte solute is dissolved in 1 kg of water, what is the expected change in freezing point?
A.0.0 °C
B.-1.86 °C
C.-3.72 °C
D.-5.58 °C
Solution
The freezing point depression for 1 mole of a non-electrolyte solute in 1 kg of water is -1.86 °C.
Correct Answer: B — -1.86 °C
Q. If 1 mole of NaCl is dissolved in 1 kg of water, what is the expected van 't Hoff factor (i)?
A.1
B.2
C.3
D.4
Solution
NaCl dissociates into 2 ions (Na+ and Cl-), so the van 't Hoff factor (i) is 2.
Correct Answer: B — 2
Q. If 1 mole of solute is dissolved in 1 liter of solution, what is the concentration in terms of molarity?
A.1 M
B.2 M
C.0.5 M
D.0.25 M
Solution
Molarity (M) = moles of solute / liters of solution = 1 mole / 1 L = 1 M.
Correct Answer: A — 1 M
Q. If 10 grams of calcium carbonate (CaCO3) decomposes, how many grams of calcium oxide (CaO) are produced?
A.5 g
B.10 g
C.8 g
D.7 g
Solution
The balanced equation is CaCO3 → CaO + CO2. The molar mass of CaCO3 is 100 g/mol and CaO is 56 g/mol. Thus, 10 g of CaCO3 produces (10 g / 100 g/mol) x 56 g/mol = 5.6 g of CaO.
Correct Answer: C — 8 g
Q. If 10 grams of NaCl are dissolved in water, how many moles of NaCl are present? (Molar mass of NaCl = 58.5 g/mol)
A.0.17 moles
B.0.5 moles
C.1.0 moles
D.1.5 moles
Solution
Moles of NaCl = mass (g) / molar mass (g/mol) = 10 g / 58.5 g/mol = 0.171 moles.
Correct Answer: A — 0.17 moles
Q. If 10 grams of NaCl is dissolved in 500 mL of water, what is the molality of the solution? (Molar mass of NaCl = 58.5 g/mol)
A.0.34 m
B.0.17 m
C.0.85 m
D.0.50 m
Solution
Molality (m) = moles of solute / kg of solvent. Moles of NaCl = 10 g / 58.5 g/mol = 0.171 moles. Mass of water = 0.5 kg. Molality = 0.171 moles / 0.5 kg = 0.342 m.
Correct Answer: A — 0.34 m
Q. If 10 grams of NaCl is dissolved in enough water to make 500 mL of solution, what is the molality of the solution? (Molar mass of NaCl = 58.5 g/mol)
A.0.34 m
B.0.17 m
C.0.85 m
D.0.50 m
Solution
Moles of NaCl = 10 g / 58.5 g/mol = 0.171 moles. Mass of solvent (water) = 0.5 kg. Molality (m) = moles of solute / kg of solvent = 0.171 moles / 0.5 kg = 0.34 m.
Correct Answer: A — 0.34 m
Q. If 10 grams of NaOH are dissolved in water, how many moles of NaOH are present? (Molar mass of NaOH = 40 g/mol)
A.0.25 moles
B.0.5 moles
C.1 mole
D.2.5 moles
Solution
To find the number of moles, use the formula: moles = mass/molar mass. Thus, 10 g / 40 g/mol = 0.25 moles.
Correct Answer: B — 0.5 moles
Q. If 10 grams of NaOH is dissolved in 500 mL of solution, what is the molality of the solution? (Molar mass of NaOH = 40 g/mol)
A.0.5 m
B.1 m
C.2 m
D.0.25 m
Solution
Moles of NaOH = 10 g / 40 g/mol = 0.25 moles. Mass of solvent (water) = 0.5 kg. Molality (m) = moles of solute / kg of solvent = 0.25 moles / 0.5 kg = 0.5 m.
Correct Answer: B — 1 m
Q. If 10 grams of NaOH is dissolved in enough water to make 500 mL of solution, what is the molarity of the solution? (Molar mass of NaOH = 40 g/mol)
A.0.5 M
B.1 M
C.2 M
D.0.25 M
Solution
Moles of NaOH = 10 g / 40 g/mol = 0.25 moles. Molarity = 0.25 moles / 0.5 L = 0.5 M.
Correct Answer: B — 1 M
Q. If 100 g of glucose (C6H12O6) is dissolved in 1 L of solution, what is the molarity of the solution? (Molar mass of glucose = 180 g/mol)
A.0.56 M
B.1.0 M
C.0.33 M
D.0.75 M
Solution
Moles of glucose = 100 g / 180 g/mol = 0.556 moles. Molarity = moles of solute / liters of solution = 0.556 moles / 1 L = 0.56 M.
Correct Answer: A — 0.56 M
Q. If 15 grams of HCl is dissolved in 500 mL of solution, what is the molarity of the solution? (Molar mass of HCl = 36.5 g/mol)
A.0.82 M
B.1.0 M
C.0.5 M
D.1.5 M
Solution
Moles of HCl = 15 g / 36.5 g/mol = 0.41096 moles. Molarity = 0.41096 moles / 0.5 L = 0.82192 M.
