How many moles of chloride ions are present in 0.20 mol of aluminium chloride, AlCl₃?
Correct answer B. 0.60 mol
Topic / 40 questions
Fundamental Concepts of Chemistry MCQs
Fundamental Concepts of Chemistry MCQs cover the mole and Avogadro's number, stoichiometric calculations with masses, particles and gas volumes, limiting and excess reactants, and theoretical, actual and percentage yield. They help MDCAT, ECAT and FSc candidates master chemical calculations, and every question on MCQs360 shows its correct answer instantly.
- Gases 40
- Liquids 40
- Solids 40
- Chemical Equilibrium 40
- Reaction Kinetics 40
- Thermochemistry and Energetics 40
- Electrochemistry 40
- Fundamental Concepts of Chemistry 40
- Atomic Structure 39
- Chemical Bonding 39
- Alcohols and Phenols 38
- Industrial Chemistry 37
- Aldehydes and Ketones 37
- Alkyl Halides 37
- s- and p-Block Elements 37
- Chemistry of Hydrocarbons 36
- Fundamental Principles of Organic Chemistry 36
- Carboxylic Acids 36
- Transition Elements 35
- Macromolecules 35
How many moles are present in 49 g of sulphuric acid, H₂SO₄ (H = 1, S = 32, O = 16)?
Correct answer A. 0.50 mol
How many sodium ions are present in 5.85 g of sodium chloride (Na = 23, Cl = 35.5)?
Correct answer D. 6.02 × 10²²
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In the decomposition 2KClO₃ → 2KCl + 3O₂, how many moles of oxygen are produced from 4 mol of KClO₃?
Correct answer B. 6 mol
What mass of KClO₃ must be decomposed to give 9.6 g of oxygen (2KClO₃ → 2KCl + 3O₂; K = 39, Cl = 35.5, O = 16)?
Correct answer D. 24.5 g
10 g of H₂ is mixed with 64 g of O₂ and reacted (2H₂ + O₂ → 2H₂O). Which reactant is limiting and what mass of water forms?
Correct answer B. O₂ is limiting; 72 g of water
The theoretical yield of a product is 25 g and the percentage yield is 80%. What is the actual yield?
Correct answer A. 20 g
What is the mass of 3.01 × 10²³ atoms of magnesium (Mg = 24)?
Correct answer D. 12 g
Which sample contains the same number of molecules as 16 g of O₂ (H = 1, C = 12, N = 14, O = 16)?
Correct answer A. 22 g of CO₂
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The atomic mass of an element expressed in grams is called one ____
Correct answer C. gram atom
The mole is defined as the amount of substance containing as many particles as there are atoms in exactly 12 g of which isotope?
Correct answer B. Carbon-12
How many moles of ions are produced when 1 mol of Ca₃(PO₄)₂ is completely broken into its ions?
Correct answer D. 5 mol
Stoichiometric calculations based on a balanced equation assume that ____
Correct answer D. reactants are completely converted into products with no side reactions
In a limiting reactant problem, the amount of product formed should be calculated from ____
Correct answer D. the reactant that gives the smaller amount of product
The mass of one mole of formula units of an ionic compound such as NaCl, expressed in grams, is called its ____
Correct answer A. gram formula mass
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In a balanced chemical equation, the mole ratio between reactants and products is obtained from the ____
Correct answer A. coefficients of the balanced equation
6.0 g of H₂ reacts with excess N₂ (N₂ + 3H₂ → 2NH₃) and 25.5 g of NH₃ is obtained. What is the percentage yield?
Correct answer B. 75%
At STP, 11.2 dm³ of which gas has the greatest mass?
Correct answer C. CO₂
Equal masses of the following gases are taken. Which sample contains the largest number of molecules?
Correct answer C. CH₄
What is the mass of 0.20 mol of sulphuric acid, H₂SO₄ (H = 1, S = 32, O = 16)?
Correct answer B. 19.6 g
About Fundamental Concepts of Chemistry MCQs
This first chemistry unit is mainly about calculation. Questions ask you to convert between mass, moles and number of particles using molar mass and Avogadro's number, and to compare numbers of molecules in equal masses of different gases. Stoichiometry MCQs use mole ratios from balanced equations to find how much product forms or how much reactant is needed, including gas volumes at STP. Further questions identify the limiting reactant when amounts are mixed, and calculate theoretical, actual and percentage yield, for example from the thermal decomposition of calcium carbonate.
Key facts to remember
- Avogadro's number: Nₐ = 6.022 × 10²³ particles per mole.
- Number of moles n = mass ÷ molar mass (m/M), and number of particles N = n × Nₐ.
- One mole of any gas occupies 22.4 dm³ at STP (0 °C and 1 atm).
- Mole ratios in a reaction are given by the coefficients of the balanced equation.
- The limiting reactant is used up first and decides the maximum amount of product; the other reactant is in excess.
- Percentage yield = (actual yield ÷ theoretical yield) × 100.
Exams that include Fundamental Concepts of Chemistry MCQs
Pakistan
- MDCAT
- ECAT (UET)
- NUMS
- AKU
- FSc boards
India
- NEET
- JEE Main
Bangladesh
- HSC
- Medical Admission Test
How to prepare for Fundamental Concepts of Chemistry MCQs
- Always balance the equation first, then convert every given quantity to moles before using mole ratios.
- To find the limiting reactant, divide the moles of each reactant by its coefficient; the smaller value is limiting.
- For equal masses of gases, the gas with the smallest molar mass contains the most molecules.
- Learn common molar masses (H₂O = 18, CO₂ = 44, CaCO₃ = 100, NaCl = 58.5 g/mol) to save time.
Frequently asked questions
Which exams ask Fundamental Concepts of Chemistry MCQs?
Mole and stoichiometry questions appear in MDCAT, ECAT (UET), NUMS and AKU entry tests and in FSc board chemistry papers. Students in India meet the same calculations in NEET and JEE Main, and Bangladeshi students in HSC and the medical admission test.
What is a limiting reactant?
The limiting reactant is the reactant that is completely used up first in a reaction. It decides the maximum amount of product that can form, so it gives the theoretical yield. Any other reactant left over at the end is called the excess reactant.
Last reviewed October 2026