JEE Main - Chemical equations and stoichiometry calculations Online Test (MCQ Quiz)

1. What is the law of conservation of mass, as applied to chemical reactions?

A) The total mass of reactants is always greater than the total mass of products. B) The total mass of reactants is always less than the total mass of products. C) The total mass of reactants is always equal to the total mass of products. D) The mass of reactants can be greater than, less than, or equal to the mass of products.

2. Which of the following represents a balanced chemical equation?

A) H₂ + O₂ → H₂O B) 2H₂ + O₂ → 2H₂O C) H₂ + O → H₂O D) H₂ + O₂ → 2H₂O

3. What does the symbol 'g' in a chemical equation typically represent?

A) Gas B) Gram C) Solid D) Liquid

4. In the reaction 2Na + Cl₂ → 2NaCl, what is the mole ratio of sodium (Na) to chlorine (Cl₂)?

A) 1:1 B) 2:1 C) 1:2 D) 2:2

5. What is stoichiometry primarily concerned with?

A) The rate of chemical reactions. B) The energy changes during chemical reactions. C) The quantitative relationships between reactants and products in a chemical reaction. D) The physical properties of substances.

6. If 1 mole of methane (CH₄) burns completely in excess oxygen, how many moles of carbon dioxide (CO₂) are produced? (CH₄ + 2O₂ → CO₂ + 2H₂O)

A) 0.5 moles B) 1 mole C) 2 moles D) 4 moles

7. What is the molar mass of water (H₂O)? (Atomic masses: H = 1 g/mol, O = 16 g/mol)

A) 17 g/mol B) 18 g/mol C) 16 g/mol D) 32 g/mol

8. What does it mean for a reactant to be the 'limiting reactant'?

A) It is the reactant that is present in the largest amount. B) It is the reactant that is completely consumed first and determines the amount of product formed. C) It is the reactant that produces the most product. D) It is the reactant that is most expensive.

9. In the reaction N₂ + 3H₂ → 2NH₃, if 2 moles of N₂ react with 6 moles of H₂, how many moles of NH₃ are produced?

A) 2 moles B) 4 moles C) 6 moles D) 12 moles

10. What is the percentage yield of a reaction?

A) The ratio of the theoretical yield to the actual yield, multiplied by 100. B) The ratio of the actual yield to the theoretical yield, multiplied by 100. C) The total amount of product formed. D) The amount of limiting reactant used.

11. What is the empirical formula of a compound?

A) The actual number of atoms of each element in a molecule. B) The simplest whole-number ratio of atoms of each element in a compound. C) The total number of atoms in a molecule. D) The formula representing the ionic lattice structure.

12. If a reaction has a theoretical yield of 50 g and an actual yield of 40 g, what is the percentage yield?

A) 75% B) 80% C) 90% D) 125%

13. What is the molecular formula of a compound if its empirical formula is CH₂O and its molar mass is 180 g/mol? (Molar mass of CH₂O = 30 g/mol)

A) CH₂O B) C₂H₄O₂ C) C₆H₁₂O₆ D) C₃H₆O₃

14. In the reaction 2SO₂ + O₂ → 2SO₃, if 4 moles of SO₂ react, how many moles of O₂ are required?

A) 1 mole B) 2 moles C) 4 moles D) 8 moles

15. What is the term for the amount of product actually obtained in a chemical reaction?

A) Theoretical yield B) Actual yield C) Percent yield D) Limiting yield

16. What is the molar mass of glucose (C₆H₁₂O₆)? (Atomic masses: C = 12 g/mol, H = 1 g/mol, O = 16 g/mol)

A) 120 g/mol B) 180 g/mol C) 192 g/mol D) 200 g/mol

17. What is the mole ratio of products to reactants in the reaction 2H₂ + O₂ → 2H₂O?

A) 2:3 B) 3:2 C) 2:2 D) 1:2

18. If 10 grams of calcium carbonate (CaCO₃) are decomposed, producing calcium oxide (CaO) and carbon dioxide (CO₂), what is the maximum theoretical mass of CaO that can be produced? (Molar masses: CaCO₃ = 100 g/mol, CaO = 56 g/mol). CaCO₃ → CaO + CO₂

A) 5.6 g B) 10 g C) 56 g D) 100 g

19. What is the atomic mass unit (amu) defined as?

A) 1/12th the mass of a carbon-12 atom. B) The mass of a hydrogen atom. C) The mass of an oxygen atom. D) The mass of a proton.

20. What is Avogadro's number?

A) 6.022 x 10²³ B) 6.022 x 10⁻²³ C) 2.602 x 10²³ D) 2.602 x 10⁻²³

21. How many moles are in 18.066 x 10²³ molecules of a substance?

A) 1 mole B) 2 moles C) 3 moles D) 0.5 moles

22. What is the volume occupied by 1 mole of any ideal gas at Standard Temperature and Pressure (STP)?

A) 22.4 Liters B) 11.2 Liters C) 44.8 Liters D) 1 Liter

23. What is the molarity of a solution?

A) Moles of solute per kilogram of solvent. B) Moles of solute per liter of solution. C) Mass of solute per liter of solution. D) Mass of solute per kilogram of solution.

24. If 0.5 moles of NaCl are dissolved in enough water to make 2 liters of solution, what is the molarity?

A) 0.25 M B) 0.5 M C) 1.0 M D) 2.0 M

25. What is the mass percentage of carbon in methane (CH₄)? (Atomic masses: C = 12 g/mol, H = 1 g/mol)

A) 25% B) 75% C) 80% D) 90%

26. In the reaction A + 2B → C, if 4 moles of A react with 6 moles of B, which is the limiting reactant?

A) A B) B C) C D) Neither A nor B

27. What is the purpose of balancing chemical equations?

A) To ensure the law of conservation of energy is obeyed. B) To ensure the law of conservation of mass is obeyed. C) To indicate the physical states of reactants and products. D) To show the reaction rate.

28. What is the term for the calculation of the relative amounts of substances in a chemical reaction?

A) Thermodynamics B) Kinetics C) Stoichiometry D) Equilibrium

29. What is the molar mass of sulfuric acid (H₂SO₄)? (Atomic masses: H = 1 g/mol, S = 32 g/mol, O = 16 g/mol)

A) 64 g/mol B) 82 g/mol C) 98 g/mol D) 100 g/mol

30. If 2 moles of hydrogen gas (H₂) react with 1 mole of oxygen gas (O₂) to form water (H₂O), how many moles of water are produced?

A) 1 mole B) 2 moles C) 3 moles D) 4 moles

31. What does the arrow (→) in a chemical equation signify?

A) Reversible reaction B) Equilibrium C) Yields or produces D) Heat is required

32. What is the mole concept used to relate?

A) Mass and volume. B) Mass and number of particles. C) Volume and number of particles. D) Energy and mass.

33. In the reaction C + O₂ → CO₂, if 12 g of carbon reacts completely with oxygen, how many grams of CO₂ are produced? (Atomic masses: C = 12 g/mol, O = 16 g/mol)

A) 16 g B) 24 g C) 32 g D) 44 g

34. What is the term for the number of moles of solute per kilogram of solvent?

A) Molarity B) Molality C) Mole fraction D) Normality

35. If the empirical formula of a compound is CH₂ and its molar mass is 28 g/mol, what is its molecular formula? (Molar mass of CH₂ = 14 g/mol)

A) CH₂ B) C₂H₄ C) C₃H₆ D) C₄H₈

36. What does the symbol '(aq)' in a chemical equation represent?

A) Aqueous solution B) Acidic solution C) Alkaline solution D) Gas

37. In the reaction 2Al + 3Cl₂ → 2AlCl₃, if 1 mole of Al reacts with 1.5 moles of Cl₂, how many moles of AlCl₃ are formed?

A) 0.5 moles B) 1 mole C) 1.5 moles D) 2 moles

38. What is the mass of 2 moles of Helium (He) gas? (Atomic mass of He = 4 g/mol)

A) 2 g B) 4 g C) 8 g D) 16 g

39. What is the definition of a mole?

A) The mass of a substance in grams. B) The number of particles equal to Avogadro's number. C) The amount of substance containing as many elementary entities as there are atoms in 0.012 kg of carbon-12. D) The volume occupied by a gas at STP.

40. What is the percentage composition of oxygen in water (H₂O)? (Atomic masses: H = 1 g/mol, O = 16 g/mol)

A) 11.1% B) 88.9% C) 50% D) 75%

41. In the reaction 2H₂O₂ → 2H₂O + O₂, if 4 moles of H₂O₂ decompose, how many moles of O₂ are produced?

A) 1 mole B) 2 moles C) 4 moles D) 8 moles

42. What is the relationship between empirical formula and molecular formula?

A) The molecular formula is always simpler than the empirical formula. B) The molecular formula is always a whole-number multiple of the empirical formula. C) The empirical formula and molecular formula are always the same. D) The empirical formula represents the number of atoms in a molecule.

43. What is the mass of 1 mole of electrons, given the mass of an electron is 9.109 x 10⁻³¹ kg?

A) 5.486 x 10⁻⁷ kg B) 9.109 x 10⁻⁴ kg C) 1.672 x 10⁻²⁷ kg D) 6.022 x 10²³ kg

44. What is the mole fraction of a component in a solution?

A) Moles of component / Total moles of solution B) Moles of component / Moles of solvent C) Moles of component / Moles of solute D) Mass of component / Total mass of solution

45. What is the principle behind calculating the theoretical yield of a reaction?

A) Using the actual yield to determine the maximum possible product. B) Using the stoichiometry of the balanced equation and the amount of limiting reactant. C) Assuming all reactants are completely consumed. D) Measuring the energy released during the reaction.

46. If 100 mL of a 0.1 M HCl solution is mixed with 100 mL of a 0.1 M NaOH solution, what is the concentration of NaCl in the resulting solution? (Assume complete neutralization)

A) 0 M B) 0.05 M C) 0.1 M D) 0.2 M

47. What is the mass of 3 moles of sodium chloride (NaCl)? (Atomic masses: Na = 23 g/mol, Cl = 35.5 g/mol)

A) 58.5 g B) 117 g C) 175.5 g D) 234 g

48. What information can be directly obtained from a balanced chemical equation?

A) The time required for the reaction to complete. B) The physical states of all reactants and products. C) The mole ratios between reactants and products. D) The energy change of the reaction.

49. What is the process of determining the amount of a substance in a sample using a chemical reaction with a reagent of known concentration called?

A) Titration B) Gravimetry C) Spectroscopy D) Chromatography

50. If 8 grams of oxygen (O₂) react completely, how many moles of oxygen atoms are involved? (Atomic mass of O = 16 g/mol)

A) 0.25 moles B) 0.5 moles C) 1 mole D) 2 moles

Chemical equations and stoichiometry calculations - Online Test

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