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1. The SI unit of pressure is

A. atmosphere B. Pascal C. bar D. torr

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2. Which of the following has the highest number of molecules?

A. 1 g of CO₂ B. 1 g of N₂ C. 1 g of H₂ D. 1 g of O₂

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3. In the reaction 2Al + 6HCl → 2Al³⁺ + 6Cl⁻ + 3H₂, the volume of hydrogen gas produced at STP per mole of aluminum reacted is

A. 22.4 L B. 11.2 L C. 44.8 L D. 33.6 L

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4. The percentage of nitrogen in urea (NH₂CONH₂) is approximately

A. 46% B. 35% C. 28% D. 18%

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5. The limiting reagent in a reaction is

A. none of these B. the reagent in excess C. the reagent that determines the extent of the reaction D. the fastest reacting reagent

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6. The mass of 0.5 moles of Na₂CO₃·10H₂O (molar mass = 286 g/mol) is

A. 57.2 g B. 143 g C. 286 g D. 71.5 g

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7. One mole of magnesium nitride on reaction with an excess of water gives

A. one mole of ammonia B. one mole of nitric acid C. two moles of ammonia D. two moles of nitric acid

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8. Which of the following has the maximum number of molecules?

A. 1 g of CO₂ B. 1 g of H₂ C. 1 g of O₂ D. 1 g of N₂

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9. Which of the following solutions has the highest normality?

A. 1 M HCl B. 1 M H₃PO₄ C. 1 M H₂SO₄ D. 1 M CH₃COOH

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10. If 2 g of hydrogen reacts with 16 g of oxygen, the amount of water formed is

A. 16 g B. 2 g C. 20 g D. 18 g

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11. The mole fraction of a solute in a solution is

A. the ratio of the mass of solute to the mass of solvent B. the ratio of the volume of solute to the volume of solvent C. the ratio of the moles of solute to the total moles of solution D. the ratio of the moles of solute to the moles of solvent

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12. The volume of 0.1 M HCl required to completely neutralize 25 mL of 0.1 M NaOH is

A. 50 mL B. 25 mL C. 10 mL D. 100 mL

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13. The empirical formula of a compound is CH₂O, and its molecular weight is 180 g/mol. The molecular formula is

A. C₆H₁₂O₆ B. C₃H₆O₃ C. C₂H₄O₂ D. C₄H₈O₄

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14. The molarity of a solution containing 5.85 g of NaCl (molar mass = 58.5 g/mol) dissolved in 500 mL of solution is

A. 0.2 M B. 1.0 M C. 0.5 M D. 0.1 M

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15. The empirical formula of a compound with 40% carbon, 6.7% hydrogen, and 53.3% oxygen is

A. C6H12O6 B. C2H4O2 C. CH2O D. C3H6O3

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16. The number of atoms in 0.1 moles of a diatomic gas is

A. 3.011 × 10²³ B. 1.204 × 10²² C. 1.204 × 10²³ D. 6.022 × 10²²

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17. The molecular weight of glucose (C6H12O6) is

A. 160 g/mol B. 150 g/mol C. 180 g/mol D. 120 g/mol

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18. Volume occupied by one molecule of water (density = 1 g/cm³) is

A. 1.0 × 10⁻²³ cm³ B. 9.0 × 10⁻²³ cm³ C. 3.0 × 10⁻²³ cm³ D. 6.023 × 10⁻²³ cm³

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19. What is the molar mass of Na₂SO₄?

A. 144 g/mol B. 142 g/mol C. 146 g/mol D. 148 g/mol

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20. The equivalent weight of a substance is

A. its molecular weight divided by Avogadro’s number B. its molecular weight multiplied by Avogadro’s number C. its molecular weight multiplied by the number of moles D. its molecular weight divided by the number of moles of electrons transferred