Free Fundamental Concepts of Chemistry MCQs with Answers
894 Fundamental Concepts of Chemistry MCQs from Chemistry, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
Mole calculations connect mass, number of particles and Avogadro's number, while balanced equations provide the mole ratios used in stoichiometry. Questions cover limiting and excess reactants, theoretical yield and percentage yield, including identifying which reactant is consumed first and comparing the actual product with the maximum possible product.
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Read the Fundamental Concepts of Chemistry notesFree MDCAT chapter notes with key terms894 questions · page 2 of 45
- A. 63.6%
- B. 77.8%
- C. 87.5%
- D. 92.5%
Explanation: Four grams of hydrogen is 2 moles and 32 g of oxygen is 1 mole, which is exactly the 2 to 1 ratio the equation requires, so neither is in…
Correct answer: 77.8%- A. 11.2 dm3
- B. 22.4 dm3
- C. 10 dm3
- D. 58 dm3
Explanation: Balanced properly the equation is 2H2 plus O2 giving 2H2O, so one mole of water needs one mole of hydrogen, and one mole of any gas…
Correct answer: 22.4 dm3- A. 20%
- B. 25%
- C. 45%
- D. 80%
Explanation: Percentage yield is actual divided by theoretical multiplied by 100, so 20 over 25 multiplied by 100 gives 80 per cent.
Correct answer: 80%- A. 20 g
- B. 25 g
- C. 30 g
- D. 40 g
Explanation: Rearranging the percentage yield formula, the theoretical yield is the actual yield multiplied by 100 and divided by the percentage, so 20…
Correct answer: 25 g- A. 2.05 gram
- B. 3.05 gram
- C. 4.05 gram
- D. 5.05 gram
Explanation: The balanced reaction is P4 + 5O2 -> P4O10. Moles of P4 = 1.33 g ÷ 123.9 g/mol = 0.0107 mol, while the 5.07 g O2 provides 5.07 g ÷ 32.0…
Correct answer: 3.05 gram- A. is taken in lesser quantity in grams as compared to other reactants
- B. is taken in lesser quantity in volume as compared to other reactants
- C. gives the maximum amount of the product which is required
- D. gives the minimum amount of the product under consideration
Explanation: The limiting reactant is consumed first according to the balanced equation, so it determines the maximum, or minimum possible under the…
Correct answer: gives the minimum amount of the product under consideration- A. 6.02 x 10^23
- B. 12.04 x 10^25
- C. 18.06 x 10^23
- D. 24.08 x 10^23
Explanation: One mole contains 6.022 x 10^23 molecules, so 4 moles contain 4 x 6.022 x 10^23 = 24.088 x 10^23 molecules, which is approximately 24.08 x…
Correct answer: 24.08 x 10^23- A. 190amu
- B. 188amu
- C. 180amu
- D. 98amu
Explanation: The molecular mass of glucose is calculated as (6 x 12 amu) + (12 x 1 amu) + (6 x 16 amu) = 72 amu + 12 amu + 96 amu = 180 amu.
Correct answer: 180amu- A. NH3
- B. C12H22O11
- C. C6H12O6
- D. C6H6
Explanation: Glucose is a monosaccharide with the molecular formula C6H12O6, showing six carbon atoms, twelve hydrogen atoms, and six oxygen atoms in…
Correct answer: C6H12O6- A. NH3
- B. C12H22O11
- C. C6H12O6
- D. C6H6
Explanation: Sucrose is a disaccharide formed from glucose and fructose, with the molecular formula C12H22O11 after loss of water during condensation.
Correct answer: C12H22O11- A. 1.5
- B. 0.25
- C. 0.125
- D. None of These
Explanation: The molar mass of CS2 is 12 g/mol + (2 x 32 g/mol) = 76 g/mol. Therefore, moles = mass/molar mass = 9.5 g / 76 g/mol = 0.125 mol.
Correct answer: 0.125- A. H2SO4
- B. HClO4
- C. O3
- D. H2C2O4
Explanation: One mole of each compound contains the same number of molecules, so compare atoms in one molecule: H2SO4 has 7 atoms, HClO4 has 6, O3 has…
Correct answer: H2C2O4- A. 22%
- B. 11.11%
- C. 31.13%
- D. 15.15%
Explanation: In 1 mole of water, H2O, the mass of hydrogen is 2 g and the molar mass of water is 18 g, so hydrogen by mass is (2 g / 18 g) x 100 =…
Correct answer: 11.11%- A. 14.34%
- B. 18.56%
- C. 13.86%
- D. None of these
Explanation: The molar mass of KNO3 is 39.10 g/mol + 14.01 g/mol + 3 x 16.00 g/mol = 101.11 g/mol.
Correct answer: 13.86%- A. 57% N
- B. 73% N
- C. 46% N
- D. 53% N
Explanation: Urea is CO(NH2)2, with molar mass 12 + 16 + 2(14) + 4(1) = 60 g mol^-1.
Correct answer: 46% N- A. C2H2O4
- B. CH2
- C. CH2O
- D. CHO2
Explanation: Convert each mass to moles: carbon = 24 g ÷ 12 g mol^-1 = 2 mol, hydrogen = 2 g ÷ 1 g mol^-1 = 2 mol, and oxygen = 64 g ÷ 16 g mol^-1 = 4…
Correct answer: CHO2- A. 53.4 grams
- B. 54.4 grams
- C. 55.4 grams
- D. 56.4 grams
Explanation: The molar mass of NH3 is 14.0 g/mol + 3 x 1.0 g/mol = 17.0 g/mol, so mass = 3.2 mol x 17.0 g/mol = 54.4 g.
Correct answer: 54.4 grams- A. 0.2 moles
- B. 0.3 moles
- C. 0.4 moles
- D. 0.5 moles
Explanation: The molar mass of CaCl2 is 40.0 g/mol + 2 x 35.5 g/mol = 111.0 g/mol, so moles = 22.2 g / 111.0 g/mol = 0.20 mol.
Correct answer: 0.2 moles- A. 64.5%
- B. 65.6%
- C. 63.5%
- D. 61.5%
Explanation: The molar mass of AgNO3 is 107.9 g/mol + 14.0 g/mol + 3(16.0 g/mol) = 169.9 g/mol.
Correct answer: 63.5%- A. 74% Fe
- B. 75% Fe
- C. 77% Fe
- D. 78% Fe
Explanation: Percentage of iron = (mass of iron ÷ mass of ore) x 100 = (27.9 g ÷ 35.8 g) x 100 = 77.93%, which rounds to 78% Fe.
Correct answer: 78% Fe