Atomic and molecular masses and mole concept - Question Bank

1. What is the number of moles in 10 grams of hydrogen gas (H₂)? (Atomic mass H=1)
A) 5 moles
B) 10 moles
C) 20 moles
D) 0.5 moles
2. The molar mass of a compound is numerically equal to its relative molecular mass multiplied by:
A) 1 g/mol
B) 1 amu
C) 1 kg/mol
D) Avogadro's number
3. What is the mole fraction of solute if 2 moles of solute are dissolved in 8 moles of solvent?
A) 0.2
B) 0.25
C) 0.5
D) 0.8
4. The number of moles of solute per kilogram of solvent is:
A) Molarity
B) Molality
C) Mole fraction
D) Normality
5. What is the mass of 0.2 moles of sulfuric acid (H₂SO₄)? (Atomic masses H=1, S=32, O=16)
A) 9.8 g
B) 19.6 g
C) 49 g
D) 98 g
6. Which of the following has the largest number of atoms?
A) 1 mole of H₂
B) 1 mole of O₂
C) 1 mole of N₂
D) 1 mole of He
7. If a solution has a molarity of 0.5 M and a volume of 2 liters, how many moles of solute are present?
A) 0.25 moles
B) 0.5 moles
C) 1 mole
D) 2 moles
8. What is the number of moles of hydrogen atoms in 1 mole of methane (CH₄)?
A) 1 mole
B) 2 moles
C) 3 moles
D) 4 moles
9. The term 'gram atomic mass' is synonymous with:
A) Atomic mass in amu
B) Molecular mass
C) Molar mass of an element
D) Equivalent mass
10. What is the number of moles in 100 grams of calcium carbonate (CaCO₃)? (Atomic masses Ca=40, C=12, O=16)
A) 1 mole
B) 2 moles
C) 0.5 moles
D) 100 moles
11. How many grams of oxygen gas (O₂) are there in 2 moles of O₂? (Atomic mass O=16)
A) 16 g
B) 32 g
C) 64 g
D) 96 g
12. What is the molar mass of ammonia (NH₃)? (Atomic masses N=14, H=1)
A) 15 g/mol
B) 16 g/mol
C) 17 g/mol
D) 18 g/mol
13. The relative atomic mass of an element is the ratio of the average mass of atoms of an element to:
A) The mass of an atom of carbon-14
B) The mass of an atom of carbon-12
C) 1/12th the mass of an atom of carbon-12
D) 1/16th the mass of an atom of oxygen-16
14. Which of the following has the smallest mass?
A) 1 mole of electrons
B) 1 mole of protons
C) 1 mole of neutrons
D) 1 mole of hydrogen atoms
15. How many molecules are present in 36 grams of water (H₂O)? (Molar mass of H₂O ≈ 18 g/mol, N_A = 6.022 x 10^23 mol⁻¹)
A) 6.022 x 10^23 molecules
B) 1.2044 x 10^24 molecules
C) 0.5 x 6.022 x 10^23 molecules
D) 36 x 6.022 x 10^23 molecules
16. What is the total number of moles of atoms in 1 mole of calcium phosphate (Ca₃(PO₄)₂)?
A) 7 moles
B) 8 moles
C) 9 moles
D) 13 moles
17. What is the mole fraction of water in a solution prepared by dissolving 18 g of glucose (C₆H₁₂O₆) in 180 g of water?
A) 0.5
B) 0.8
C) 0.9
D) 1.0
18. The number of moles of solute in 1 kg of solvent is called:
A) Molarity
B) Mole fraction
C) Molality
D) Normality
19. What is the mass of 0.1 moles of sodium hydroxide (NaOH)? (Atomic masses Na=23, O=16, H=1)
A) 4 g
B) 40 g
C) 0.4 g
D) 400 g
20. How many moles are present in 44 grams of carbon dioxide (CO₂)? (Molar mass of CO₂ ≈ 44 g/mol)
A) 0.5 moles
B) 1 mole
C) 2 moles
D) 44 moles
21. The mass of a substance containing N_A entities is equal to its:
A) Atomic mass
B) Molecular mass
C) Molar mass
D) Equivalent mass
22. What is the molar mass of ozone (O₃)? (Atomic mass O=16)
A) 16 g/mol
B) 32 g/mol
C) 48 g/mol
D) 96 g/mol
23. Which of the following has the largest number of molecules?
A) 18 g of H₂O
B) 16 g of O₂
C) 14 g of N₂
D) 2 g of H₂
24. What is the number of moles of oxygen atoms in 2 moles of carbon dioxide (CO₂)?
A) 1 mole
B) 2 moles
C) 3 moles
D) 4 moles
25. If the empirical formula of a compound is CH₂O and its molar mass is 180 g/mol, what is its molecular formula?
A) CH₂O
B) C₂H₄O₂
C) C₆H₁₂O₆
D) C₃H₆O₃
26. What is the concentration of ions in a 0.1 M solution of CaCl₂?
A) 0.1 M
B) 0.2 M
C) 0.3 M
D) 0.4 M
27. The term 'gram molecular mass' is synonymous with:
A) Atomic mass
B) Molecular mass in amu
C) Molar mass
D) Equivalent mass
28. What is the number of moles in 1 kg of substance?
A) 1 / Molar mass (in kg/mol)
B) 1000 / Molar mass (in g/mol)
C) Molar mass (in g/mol) / 1000
D) 1000 x Molar mass (in g/mol)
29. How many grams of NaCl are there in 0.1 moles of NaCl? (Atomic masses Na=23, Cl=35.5)
A) 5.85 g
B) 58.5 g
C) 0.585 g
D) 585 g
30. What is the molar mass of glucose (C₆H₁₂O₆)? (Atomic masses C=12, H=1, O=16)
A) 180 g/mol
B) 192 g/mol
C) 178 g/mol
D) 200 g/mol
31. The number of moles of a substance is calculated as:
A) Mass / Molar mass
B) Molar mass / Mass
C) Number of particles / Avogadro's number
D) Both a and c
32. Which of the following has the largest mass?
A) 1 mole of Helium
B) 1 mole of Oxygen
C) 1 mole of Nitrogen
D) 1 mole of Hydrogen
33. What is the mass of one molecule of water (H₂O)? (Atomic masses H=1, O=16, N_A = 6.022 x 10^23 mol⁻¹)
A) 18 amu
B) 18 grams
C) 3.0 x 10⁻²³ g
D) 18 x 6.022 x 10^23 g
34. How many atoms are present in 1 mole of gold (Au)?
A) 1 atom
B) 6.022 x 10^23 atoms
C) 197 atoms
D) 197 x 6.022 x 10^23 atoms
35. What is the total number of moles of atoms in 1 mole of sodium sulfate (Na₂SO₄)?
A) 3 moles
B) 4 moles
C) 5 moles
D) 7 moles
36. If a solution contains 1 mole of solute and 4 moles of solvent, what is the mole fraction of the solute?
A) 0.2
B) 0.25
C) 0.8
D) 1.0
37. What is the mole fraction of a solute if the mole fraction of the solvent is 0.7?
A) 0.3
B) 0.7
C) 1.0
D) 1.7
38. The number of moles of solute in 1 liter of solution is called:
A) Molality
B) Mole fraction
C) Normality
D) Molarity
39. What is the mass of 0.5 moles of sulfuric acid (H₂SO₄)? (Atomic masses H=1, S=32, O=16)
A) 49 g
B) 98 g
C) 0.5 g
D) 196 g
40. How many moles are present in 18 grams of water (H₂O)? (Molar mass of H₂O ≈ 18 g/mol)
A) 0.5 moles
B) 1 mole
C) 2 moles
D) 18 moles
41. What is the mass of 2 moles of carbon dioxide (CO₂)? (Atomic mass C=12, O=16)
A) 22 g
B) 44 g
C) 88 g
D) 176 g
42. If 1 mole of NaCl is dissolved in water, how many moles of Na⁺ ions are produced?
A) 0.5 moles
B) 1 mole
C) 2 moles
D) 23 moles
43. Which of the following represents the molecular mass of methane (CH₄)?
A) 12 amu
B) 16 amu
C) 18 amu
D) 20 amu
44. The molar mass of a substance is numerically equal to its:
A) Atomic mass in amu
B) Molecular mass in amu
C) Equivalent weight
D) Vapor density
45. What is the SI unit for the amount of substance?
A) Gram
B) Kilogram
C) Mole
D) Molecule
46. One mole of any substance contains the same number of entities (atoms, molecules, ions, etc.) as there are atoms in:
A) 12 grams of carbon-14
B) 12 grams of carbon-12
C) 16 grams of oxygen-16
D) 1 gram of hydrogen
47. Avogadro's number (N_A) is approximately:
A) 6.022 x 10^20
B) 6.022 x 10^21
C) 6.022 x 10^22
D) 6.022 x 10^23
48. What is the molar mass of water (H₂O), given atomic masses H=1.008 amu, O=15.999 amu?
A) 16.000 g/mol
B) 17.007 g/mol
C) 18.015 g/mol
D) 19.016 g/mol
49. Which element has an atomic mass closest to 1 amu?
A) Helium
B) Hydrogen
C) Lithium
D) Carbon
50. What is the atomic mass unit (amu) defined as?
A) 1/12th the mass of an atom of carbon-14
B) 1/12th the mass of an atom of carbon-12
C) 1/16th the mass of an atom of oxygen-16
D) The mass of a proton
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