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 30 of 45
- A. 148 g
- B. 138 g
- C. 157 g
- D. 166 g
Explanation: Phosphoric acid is H3PO4. Its molar mass is 97.9 g/mol. To find the mass we use the formula;mass = moles × molar massmass = 1.69×97.994=166g
Correct answer: 166 g- A. The ratio of actual yield to theoretical yield multiplied by 100
- B. The difference between theoretical yield and actual yield
- C. The ratio of theoretical yield to actual yield multiplied by 100
- D. The actual yield divided by 100
Explanation: The percent yield equation is:percent yield = actual yield / theoretical yield x 100%The percent yield is the ratio of the actual yield…
Correct answer: The ratio of actual yield to theoretical yield multiplied by 100583. A polymer of empirical formula CH2 has molar mass of 28000 gmol-1. Its molecular formula will be
- A. 100 times that of its empirical formula
- B. 200 times that of its empirical formula
- C. 500 times that of its empirical formula
- D. 2000 times that of its empirical formula
Explanation: The empirical mass of CH4 is 12+2=14g. Dividing molar mass by observed mass will give us the answer: 28000/14=2000 times.
Correct answer: 2000 times that of its empirical formula- A. H2
- B. N2
- C. O2
- D. Both H2 and N2
Explanation: The number of atoms in an element is proportional to the number of moles of that element.
Correct answer: O2585. An organic compound has C=40%, H=6.67% and O=53.3% What is the empirical formula of the compound?
- A. CH3O
- B. C2H2O
- C. CH2O
- D. C2H6O
Explanation: Emprical formula can be calculated as follows; Number of atoms of C = 40/12 =3.33 Number of atoms of H = 6.68/1 = 6.67 Number of atoms of…
Correct answer: CH2O- A. P2O5
- B. P2O3
- C. P5O2
- D. PO2
Explanation: Let the total mass of the compound be 100g.Given that the percentage of oxygen is 43.6%.
Correct answer: P2O3- A. H
- B. C
- C. P
- D. Cl
Explanation: The correct element used as the standard to determine the atomic mass of other elements is B. C. (carbon).
Correct answer: C- A. Carbon
- B. Helium
- C. Hydrogen
- D. Nitrogen
Explanation: The correct element used as the reference to determine atomic weights is A. Carbon.
Correct answer: Carbon- A. 76 cm Hg
- B. 769 mm Hg
- C. 760 torr
- D. 101325 Pa
Explanation: Option B is correct.The answer is 769 mm Hg. 1 atm is equal to 760 mm Hg, so 769 mm Hg is slightly greater than 1 atm.
Correct answer: 769 mm Hg- A. N₂O
- B. NO₂
- C. N₂O₃
- D. N₂O₅
Explanation: To determine the empirical formula, we need to find the simplest whole-number ratio of the atoms.Calculate the moles of each…
Correct answer: N₂O₅- A. Atoms
- B. Molecules
- C. Particles
- D. All of the above
Explanation: Atoms are the fundamental building blocks of matter. They are incredibly small particles that make up everything around us.
Correct answer: Atoms- A. 6.022 x 10^23 electrons
- B. 1.204 x 10^24 electrons
- C. 3.011 x 10^23 electrons
- D. 2.409 x 10^24 electrons
Explanation: Determine the molar mass of methane (CH4): The molar mass of CH4 is 12.01 g/mol (for carbon) + 4 * 1.01 g/mol (for hydrogen) = 16.05…
Correct answer: 6.022 x 10^23 electrons593. When describing the isotopes of the same element, the most accurate statement is that they have:
- A. The same atomic number but different atomic masses
- B. The same atomic mass but different atomic numbers
- C. Different numbers of protons and neutrons
- D. Different numbers of electrons
Explanation: This is the correct answer. Isotopes are atoms of the same element that have the same number of protons (atomic number) but different…
Correct answer: The same atomic number but different atomic masses- A. Compound
- B. Element
- C. Mixture
- D. Solution
Explanation: This is the correct answer. A compound is a pure substance made up of two or more different elements chemically combined in a fixed ratio.
Correct answer: Compound- A. Consumed reactant
- B. Limiting reactant
- C. Excess reactant
- D. Non-reacted reactant
Explanation: The limiting reactant is the reactant that is consumed first in a chemical reaction, thereby limiting the amount of product that can be…
Correct answer: Limiting reactant- A. C3H6O3
- B. C4H4O2
- C. C8H8O4
- D. C6H6O3
Explanation: The empirical mass formula is 42, i.e., [2(12) + 2(1) + 16]. Multiplying the empirical formula mass by 4 will result in a molecular mass…
Correct answer: C8H8O4- A. 67,000 times
- B. 68,000 times
- C. 65,000 times
- D. 69,000 times
Explanation: Each Haemoglobin molecule is made up of nearly 10,000 atoms and is 68000 times heavier than a Hydrogen atom.
Correct answer: 68,000 times- A. Atoms
- B. Particles
- C. Molecules
- D. None of these
Explanation: 22.414 dm3 of each gas has a different mass however the very same number of particles.
Correct answer: Particles- A. Dots
- B. Atoms
- C. Sub particles
- D. Electrons
Explanation: Atomicity refers to the number of atoms present in a single molecule of an element, substance, or compound.
Correct answer: Atoms- A. 0.5
- B. 0.3
- C. 0.2
- D. 0.1
Explanation: 22.4 litres of CO2 has 44 grams weight. It is 1 mole.In 11.2 litres of CO2 , it weighs only 22 grams. It is 0.5 mole.
Correct answer: 0.5