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
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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
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Q. Identify the hybridization of the central atom in C2H4.
A.
sp
B.
sp2
C.
sp3
D.
dsp3
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Solution
The central carbon atoms in C2H4 are sp2 hybridized, forming a double bond between them.
Correct Answer: B — sp2
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Q. Identify the hybridization of the central atom in CO2.
A.
sp
B.
sp2
C.
sp3
D.
dsp3
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Solution
Carbon in CO2 is sp hybridized, forming two double bonds with oxygen.
Correct Answer: A — sp
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Q. Identify the hybridization of the central atom in NH3.
A.
sp
B.
sp2
C.
sp3
D.
dsp3
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Solution
The nitrogen atom in NH3 is sp3 hybridized, forming three bonds and one lone pair.
Correct Answer: C — sp3
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Q. Identify the hybridization of the nitrogen atom in NH3.
A.
sp
B.
sp2
C.
sp3
D.
dsp2
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Solution
The nitrogen atom in NH3 is sp3 hybridized, forming three N-H bonds and one lone pair.
Correct Answer: C — sp3
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Q. If 0.1 M of a strong acid is mixed with 0.1 M of a strong base, what will be the resulting pH?
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Solution
Strong acid and strong base neutralize each other, resulting in a neutral solution with pH = 7.
Correct Answer: B — 7
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Q. If 0.1 M of a weak acid has a pH of 4.0, what is the Ka of the acid?
A.
1 x 10^-4
B.
1 x 10^-5
C.
1 x 10^-6
D.
1 x 10^-7
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Solution
Using the formula Ka = [H+]^2 / [HA], where [H+] = 10^(-4) M and [HA] = 0.1 M, we find Ka = (10^-4)^2 / 0.1 = 1 x 10^-5.
Correct Answer: B — 1 x 10^-5
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Q. If 0.5 mol of a non-volatile solute is dissolved in 1 kg of water, what is the vapor pressure lowering? (Vapor pressure of pure water = 23.76 mmHg)
A.
1.88 mmHg
B.
2.88 mmHg
C.
3.88 mmHg
D.
4.88 mmHg
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Solution
Vapor pressure lowering = (n_solute / n_solvent) * P°_solvent = (0.5 / 55.5) * 23.76 = 1.88 mmHg
Correct Answer: A — 1.88 mmHg
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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
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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
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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
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Solution
Concentration (M) = moles of solute / liters of solution = 0.5 moles / 1 L = 0.5 M.
Correct Answer: A — 0.5 M
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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
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Solution
Concentration (M) = moles of solute / liters of solution = 0.5 moles / 1 L = 0.5 M.
Correct Answer: A — 0.5 M
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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
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Solution
Molarity (M) = moles of solute / liters of solution = 0.5 moles / 1 L = 0.5 M.
Correct Answer: A — 0.5 M
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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
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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
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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
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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
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Q. If 1 liter of a 2 M solution is diluted to 3 liters, what is the new molarity?
A.
0.67 M
B.
1 M
C.
1.5 M
D.
2 M
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Solution
Using the dilution formula M1V1 = M2V2, (2 M)(1 L) = M2(3 L) => M2 = 2/3 = 0.67 M.
Correct Answer: A — 0.67 M
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Q. If 1 mol of NaCl is dissolved in 1 kg of water, how many particles are present in solution?
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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
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Q. If 1 mol of NaCl is dissolved in 1 kg of water, what is the expected van 't Hoff factor (i)?
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Solution
NaCl dissociates into 2 ions (Na+ and Cl-), so the van 't Hoff factor i = 2.
Correct Answer: B — 2
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Q. If 1 mol of NaCl is dissolved in water, how many particles are present in solution?
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Solution
NaCl dissociates into 2 ions (Na+ and Cl-), so 1 mol of NaCl results in 2 mol of particles.
Correct Answer: B — 2
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Q. If 1 mole of a gas occupies 22.4 L at STP, how many liters will 0.5 moles occupy?
A.
11.2 L
B.
22.4 L
C.
44.8 L
D.
5.6 L
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Solution
Volume = moles x volume per mole = 0.5 moles x 22.4 L/mole = 11.2 L.
Correct Answer: A — 11.2 L
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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
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Solution
Volume = moles x volume per mole = 0.5 moles x 22.4 L/mole = 11.2 L.
Correct Answer: A — 11.2 L
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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
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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
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Q. If 1 mole of a non-electrolyte solute is dissolved in 1 kg of water, what is the freezing point depression?
A.
0 °C
B.
1.86 °C
C.
3.72 °C
D.
5.58 °C
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Solution
The freezing point depression is calculated using the formula ΔTf = i * Kf * m. For a non-electrolyte, i = 1, Kf for water = 1.86 °C kg/mol, and m = 1 mol/kg gives ΔTf = 1.86 °C.
Correct Answer: B — 1.86 °C
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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
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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
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Q. If 1 mole of a non-volatile solute is dissolved in 1 kg of water, what is the expected change in boiling point? (Kb for water = 0.512 °C kg/mol)
A.
0.512 °C
B.
1.024 °C
C.
2.048 °C
D.
0.256 °C
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Solution
Boiling point elevation = i * Kb * m = 1 * 0.512 * 1 = 0.512 °C.
Correct Answer: B — 1.024 °C
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Q. If 1 mole of NaCl is dissolved in 1 kg of water, what is the expected van 't Hoff factor (i)?
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Solution
NaCl dissociates into 2 ions (Na+ and Cl-), so the van 't Hoff factor (i) is 2.
Correct Answer: B — 2
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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
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Solution
Molarity (M) = moles of solute / liters of solution = 1 mole / 1 L = 1 M.
Correct Answer: A — 1 M
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Q. If 10 g of CaCO3 decomposes completely, how many grams of CO2 are produced?
A.
22 g
B.
10 g
C.
44 g
D.
20 g
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Solution
10 g of CaCO3 = 0.1 moles. CaCO3 → CaO + CO2, so 0.1 moles of CO2 = 0.1 * 44 g = 4.4 g.
Correct Answer: C — 44 g
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Q. If 10 g of Na reacts with excess Cl2, what is the mass of NaCl produced?
A.
58.5 g
B.
10 g
C.
20 g
D.
30 g
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Solution
10 g of Na = 0.43 moles. Na + Cl2 → NaCl, so 0.43 moles of NaCl = 0.43 * 58.5 g = 25.2 g.
Correct Answer: A — 58.5 g
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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
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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
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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
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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
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