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 21 of 45
- A. different no. of molecules.
- B. same mass of carbon.
- C. equal no. of molecules.
- D. 0.2 moles of oxygen.
Explanation: C2H5OH 4.6/46 =0.1 mol C2H6 = 3/30 = 0.1 mol Same moles mean same no. of molecules.
Correct answer: equal no. of molecules.- A. 6 x 10^23
- B. 0.6 x 10^24
- C. 6.02 x 10^22
- D. 3.01 x 10^23
Explanation: Moles of HCl=mass/molar mass= 36.5/36.4 =1moleNumber of moles of H+ = Moles of HCl= 1 moleNumber of H+ ions= (1 mole)( 6 x 1023)= 6 x 1023…
Correct answer: 6 x 10^23- A. 22.414 dm3
- B. 0.70 dm3
- C. 22414 cm3
- D. 0.22414 m3
Explanation: Number of moles=mass/molar mass=1/32= 0.0312 moles. Use ideal gas law: PV=nRT. V=nRT/P.
Correct answer: 0.70 dm3- A. 1 :1 :1
- B. 1:16:2
- C. 2:16:2
- D. 2:16:1
Explanation: Moles of O2 =1/32= 0.03125 Moles of H2= 1/2=0.5 Moles of CH4= 1/16=0.0625 Use ideal gas law to find volumes. PV=nRT.
Correct answer: 1:16:2- A. Aromatics.
- B. Alkynes.
- C. Alkanes.
- D. Alkenes.
Explanation: The series of alkenes share the same empirical formula because they have a consistent ratio of elements.
Correct answer: Alkenes.406. Which of the followings does not represent the empirical and molecular formula of the same compound?
- A. H2O
- B. NaCl
- C. HCHO
- D. CH4
Explanation: Sodium chloride (NaCl) does not have a molecular formula in the traditional sense because it is an ionic compound, not a molecular…
Correct answer: NaCl- A. Water.
- B. Benzene.
- C. Sucrose.
- D. Glucose.
Explanation: Sucrose contains maximum thay is 45 atoms per molecule. So option C is correct.
Correct answer: Sucrose.- A. During stoichiometric calculations.
- B. The reaction is reversible.
- C. Calculating theoretical yield.
- D. All of these.
Explanation: The concept of limiting reactant is applicable because certain amoount of reactant is left behind at equilibrum and thus any reactant is…
Correct answer: The reaction is reversible.- A. 28.
- B. 46.
- C. 2.8.
- D. 4.8.
Explanation: When calcium carbonate is burnt in air it decomes to calciumoxide and carbondioxide as follows: CaCO3 (s) CaO + CO2 Molar mass of…
Correct answer: 28.- A. 2.24 dm3
- B. 22.4 dm3
- C. 1.12 dm3
- D. 112 dm3
Explanation: To determine the volume occupied by 1.4g of N2 at standard temperature and pressure (STP), we need to use the ideal gas law equation: PV =…
Correct answer: 1.12 dm3- A. 6.02 x 10^23
- B. 3.01 x 10^23
- C. 6.02 x 10^24
- D. 3.01 x 10^24
Explanation: Calculate the moles of H₂O in 9 g. moles (n) = mass (m)/molar mass (M) M(H₂O) = (2 × 1 g/mol H) + 16 g/mol O = 18 g H₂O/mol H₂O n(H₂O) = 9…
Correct answer: 6.02 x 10^23- A. Neutrons.
- B. Protons.
- C. Electrons.
- D. Atoms.
Explanation: Diamond and Gold both are different substances. Diamond is an allotrope of carbon.
Correct answer: Atoms.- A. 1.3x10 -20g
- B. 3.72 x 10^23g
- C. 5.01 x 10^-2Ig
- D. 1.4 x 10^-2Ig
Explanation: Mr of C60H122= (Ar of C x 60) + (Ar of H x 122) = (12 x 60) + ( 1 x 122 ) = 842 1 molecule = x mol 6.02 x 10 23 molecules = 1 mol x mol =…
Correct answer: 1.4 x 10^-2Ig- A. 4.0 g atoms of hydrogen.
- B. 1.81 x 10^23 molecules of CH4
- C. 3.0 g atom of carbon.
- D. 6.02 x 10^23 atoms of hydrogen.
Explanation: 1 mole of CH4 contains 1 mole of Carbon and 2 moles of Hydrogen. 12g of C (1 mole=12g) 4g of H ( 2 moles) Hence 4g of Hydrogen is the…
Correct answer: 4.0 g atoms of hydrogen.- A. 15 dm3 of H2 gas at STP.
- B. 5 dm3 of N2gas at STP.
- C. 1.5 g of H2gas.
- D. 5 g of O2gas.
Explanation: 1 mole of H2 gas = 22.4 dm3 =6.022 x 1023 molecules n (moles) = mass in g/mr = 1.5/2 = 0.75 mol 1 mol : 6.022 x 10 23 0.
Correct answer: 1.5 g of H2gas.- A. It occupies 2.24 litre at STP
- B. It corresponds to the same number of moles for 14g of CO and 14 g of N2
- C. It corresponds to 0.5 mol of CO
- D. It corresponds to 3.01 x 10^23 molecules of CO
Explanation: The question is asking for the statement which is incorrect for 14 g of CO.
Correct answer: It occupies 2.24 litre at STP- A. Expected yield
- B. Theoretical yield
- C. Actual yield
- D. Fractional yield
Explanation: Actual yield is the amount of product that is actually formed when a reaction is carried out practically in a laboratory.
Correct answer: Actual yield- A. 0.5NA
- B. NA
- C. 0.05NA
- D. 1.6NA
Explanation: Mass of methane (CH4): 0.16g Molecular mass of methane: (1 x 12) + (4 x 1) = 16 number of moles in 0.16g of CH4 = 0.16 / 16 = 0.01 mol…
Correct answer: 0.05NA- A. 2.24dm3
- B. 44.8dm3
- C. 4.48dm3
- D. 48.4dm3
Explanation: Balanced equation of decomposition of CaCO3: CaCO3 (s) → CaO (s) + CO2 (g) mass of CaCO3 : 20g molecular mass of CaCO3 : (1 x 20) + (1 x…
Correct answer: 4.48dm3- A. 1 g of H2
- B. 22 g of O2
- C. 10 g of H2
- D. 44 g of CO2
Explanation: Option C: molecular mass of H2 = 2 mass of H2 given = 10 g no of moles in 10 g of H2 : 10 / 2 = 5 mol no of molecules in 1 mole = 6.02 x…
Correct answer: 10 g of H2