Free Moles and Avogadro's Number MCQs with Answers
117 Moles and Avogadro's Number MCQs from Chemistry, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
The mole connects the microscopic number of particles with measurable mass, using Avogadro's number, 6.022 × 10²³ particles per mole. Questions involve molar mass, conversion between mass, moles and particles, percentage composition, empirical and molecular formulas, and distinguishing atoms, molecules, ions and formula units.
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117 questions · page 4 of 6
- A. 18 x 6.02 x 10^23
- B. 55.66 x 6.022 x 10^23
- C. 18 x 6.2 x 10^23
- D. 2 x 6.2 x 10^23
Explanation: Option B is correct as "1 dm3" of water is "1 liter" which weighs "1000g".
Correct answer: 55.66 x 6.022 x 10^23- A. 44g CO2 and 44g CO
- B. 16g O2 and 32g CH4
- C. 3.01 x 10^23 molecules of CO and 3.01 x 10^23 gram molecules of H2
- D. 0.5 mole of NO and 16 g O2
Explanation: Equal volumes of all ideal gases at same temperature and pressure contain equal number of moles and molecules.
Correct answer: 0.5 mole of NO and 16 g O2- A. 1.5 x 10^23
- B. 1.5 x 10^-23
- C. 0.5 x 10^23
- D. 2.4 x 10^24
Explanation: d) 2.4 x 10^24:This option is the correct answer. The Avogadro's constant is approximately 6.0 x 10^23 mol^-1, which means there are 6.0 x…
Correct answer: 2.4 x 10^24- A. 4
- B. 5
- C. 6
- D. 8
Explanation: 1 molecule of NH4NO3 = 80 amuAs 2 times 80 is 160, therefore by balanced chemical equation, 160 amu of NH4 are present in two molecules.80…
Correct answer: 4- A. C5H10 and C6H12
- B. C2H2 and C6H6
- C. C4H8 and C2H4
- D. All have the ame empirical formula
Explanation: The explanation for this question will be added soon.
Correct answer: All have the ame empirical formula66. The amount (in liters) of oxygen at STP that is required for the combustion of 4g of ethylene is:
- A. 96 liters
- B. 9.6 liters
- C. 44.8 liters
- D. 7.2 liters
Explanation: The balanced equation for this reaction will be C2H4 + 3O2 → 2CO2 + 2H2O Moles of ethylene given: moles= mass/Mr = 4/28 =1/7 moles Molar…
Correct answer: 9.6 liters- A. 1 dm3 of molecule
- B. Mass of one molecule
- C. 1 g of molecule
- D. 1 g atom
- E. 1 mole
Explanation: 1 mole is a unit of measurement that is used to count the number of atoms, molecules, or ions in a substance.
Correct answer: 1 mole- A. 5 mol
- B. 16 mol
- C. 0.5 mol
- D. 2 mol
Explanation: 1 mol of CO2 contains = 32 g O2=1 6 g O2 will be present in = 16/32 = 0.5 mol
Correct answer: 0.5 mol- A. Relationship between quantities of substances in a chemical reaction
- B. Relationship between concentration of substances
- C. Relationship between amount of substances in a chemical equation
- D. All of the above options are correct
Explanation: The relationship between the relative quantities of substances taking part in a reaction or forming a compound is called stoichiometry.
Correct answer: Relationship between quantities of substances in a chemical reaction- A. Molecular formula = empirical formula/n
- B. Molecular formula = n(empirical formula)
- C. Molecular formula = 2n(empirical formula)
- D. Empirical formula = n (Molecular formula)
Explanation: Empirical formulas show the simplest whole-number ratio of atoms in a compound, molecular formulas show the number of each type of atom in…
Correct answer: Molecular formula = n(empirical formula)- A. Mass
- B. Number of atoms
- C. Numbor ol electrons
- D. Number of molecules
Explanation: As the number of atoms is not equal the number of electrons and mass also not equal.
Correct answer: Number of molecules- A. Finding number of gram atoms of each element
- B. Percentage compostion of each element
- C. Atomic: ratio of each element
- D. Multiplication of atomic ratio with whole number
Explanation: Finding the percentage composition of each element is the first step involved in the determination of Empirical Formula ol chemical…
Correct answer: Percentage compostion of each element- A. 0.25
- B. 0.5
- C. 1.00
- D. 1.50
Explanation: One mole of CO2 has a mass of 44 g and 32 g of O2. So 16 g of O2 have 22 g of CO2 or 0.5 moles of it.
Correct answer: 0.5- A. 30.45% Carbon & 69.54% Oxygen
- B. 24.22% Carbon & 75.78% Oxygen
- C. 27 .37% carbon & 72.72% Oxygen
- D. 41.68% Carbon & 58.12% Oxygen
Explanation: The atomic weight of carbon is 12 grams and that of oxygen is 16 grams.
Correct answer: 27 .37% carbon & 72.72% Oxygen- A. 2.5 moles
- B. 2 moles
- C. 5 moles
- D. 7.5 moles
Explanation: The ratio of N2:NH3 is 1:2 so if 2.5 moles of N2 are used 5 moles of NH3 should be formed provided that hydrogen is in excess HTtT
Correct answer: 5 moles- A. 32g
- B. 24g
- C. 16g
- D. 8g
Explanation: Explanation for this question will be added soon.
Correct answer: 8g- A. 6.22 x 10^23 atoms of U-235
- B. 6.22 x 10^23 atoms of U-238
- C. 6.22 x 10^23 atoms of U-234
- D. All of these options are correct
Explanation: There are three naturally occurring isotopes of uranium: uranium-238, the heaviest and most abundant, uranium-235 and uranium-234.
Correct answer: 6.22 x 10^23 atoms of U-238- A. 1.8mg
- B. 0.184mg
- C. 0.55mg
- D. 0.64mg
Explanation: We know that:Mass of an electron = 9.1 ×10-³¹Avogadro's constant = 6.02 ×10²³Mass of one mole Electron: = 9.1 × 10-³¹ × 6.02 × 10²³ = 5.48…
Correct answer: 0.55mg- A. Shape
- B. Size
- C. Molecularity
- D. Atomicity
Explanation: OPTION A: The shape of a molecule determines its geometry. OPTION B: The size of a molecule tells us how small or big it is.
Correct answer: Atomicity- A. 24 NA
- B. 2 NA
- C. 20 NA
- D. 1 NA
Explanation: The atomic number of magnesium is 12. Mg+2 means it has lost 2 electrons. Therefore, In the Mg+2 ion, there are 12-2 = 10 electrons. No.
Correct answer: 20 NA