JEE Main - Laws of chemical combination and stoichiometry Online Test (MCQ Quiz)

1. Which law states that matter can neither be created nor destroyed in a chemical reaction?

A) Law of Definite Proportions B) Law of Multiple Proportions C) Law of Conservation of Mass D) Gay-Lussac's Law of Gaseous Volumes

2. According to the Law of Definite Proportions, a chemical compound always contains its constituent elements in a fixed ratio by:

A) Volume B) Mass C) Number of moles D) Density

3. When 10 grams of a reactant A react completely with 5 grams of reactant B, what will be the total mass of the products formed?

A) 5 grams B) 10 grams C) 15 grams D) Cannot be determined

4. Which law states that if two elements combine to form more than one compound, the masses of one element that combine with a fixed mass of the other element are in a ratio of small whole numbers?

A) Law of Conservation of Mass B) Law of Reciprocal Proportions C) Law of Multiple Proportions D) Law of Definite Proportions

5. Carbon forms two oxides, CO and CO2. If we take a fixed mass of carbon (say 12 g), the mass of oxygen that combines with it are 16 g in CO and 32 g in CO2. The ratio of masses of oxygen in CO2 to CO is:

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

6. The Law of Reciprocal Proportions states that if two different elements separately combine with a third element, then the masses of these two elements which combine with the same mass of the third element bear to each other a ratio of:

A) Simple whole numbers B) Simple fractions C) Simple integer multiples D) Complex ratios

7. If 1 gram of Hydrogen combines with 8 grams of Oxygen to form water, then 1 gram of Hydrogen will combine with how many grams of Chlorine to form HCl?

A) 8 grams B) 16 grams C) 35.5 grams D) 36.5 grams

8. Gay-Lussac's Law of Gaseous Volumes states that when gases react together, they do so in volumes which bear a simple whole number ratio to one another and to the volumes of the products, provided all gases are at the same:

A) Pressure and Temperature B) Volume and Temperature C) Pressure and Volume D) Density and Temperature

9. Consider the reaction: N2(g) + 3H2(g) -> 2NH3(g). According to Gay-Lussac's Law, 1 volume of N2 reacts with 3 volumes of H2 to produce:

A) 1 volume of NH3 B) 2 volumes of NH3 C) 3 volumes of NH3 D) 4 volumes of NH3

10. The Law of Conservation of Mass is attributed to which scientist?

A) Joseph Proust B) John Dalton C) Antoine Lavoisier D) Amedeo Avogadro

11. Avogadro's Hypothesis states that equal volumes of all gases, under the same conditions of temperature and pressure, have the same:

A) Mass B) Density C) Number of molecules D) Number of atoms

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

A) 16 g/mol B) 17 g/mol C) 18 g/mol D) 19 g/mol

13. The mole is the SI unit for amount of substance. One mole of any substance contains the same number of elementary entities as there are atoms in exactly 12 grams of:

A) Carbon-14 B) Carbon-12 C) Hydrogen-1 D) Oxygen-16

14. Avogadro's number is approximately:

A) 6.022 x 10^20 B) 6.022 x 10^22 C) 6.022 x 10^23 D) 6.022 x 10^24

15. What is the mass of 1 mole of oxygen gas (O2)? (Atomic mass of O = 16)

A) 16 grams B) 32 grams C) 8 grams D) 24 grams

16. Stoichiometry is derived from Greek words 'stoicheion' (element) and 'metron' (measure). It deals with the quantitative relationships between reactants and products in a:

A) Physical change B) Nuclear reaction C) Chemical reaction D) Phase transition

17. In the balanced chemical equation 2H2 + O2 -> 2H2O, the coefficients represent the ratio of:

A) Masses B) Volumes C) Moles D) Atoms

18. What is the empirical formula of a compound containing 40% Carbon, 6.67% Hydrogen, and 53.33% Oxygen by mass?

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

19. If the molecular formula of a compound is C6H12O6, what is its empirical formula?

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

20. Which reactant is completely consumed first in a chemical reaction and thus determines the amount of product formed?

A) Excess reactant B) Limiting reactant C) Catalyst D) Solvent

21. Consider the reaction: 2A + 3B -> 4C. If 4 moles of A react with 4 moles of B, which is the limiting reactant?

A) A B) B C) C D) Neither, it's a complete reaction

22. What is the theoretical yield of a reaction?

A) The actual amount of product obtained in an experiment B) The maximum amount of product that can be formed based on the limiting reactant C) The amount of unreacted starting material D) The amount of by-products formed

23. Percent yield is calculated as:

A) (Theoretical yield / Actual yield) x 100 B) (Actual yield / Theoretical yield) x 100 C) (Actual yield x Theoretical yield) / 100 D) (Theoretical yield x 100) / Actual yield

24. If the theoretical yield of a reaction is 50 g and the actual yield is 40 g, what is the percent yield?

A) 50% B) 75% C) 80% D) 100%

25. What is the volume occupied by 1 mole of any ideal gas at Standard Temperature and Pressure (STP: 0°C and 1 atm)?

A) 22.4 L B) 20.4 L C) 11.2 L D) 44.8 L

26. The balanced equation for the combustion of methane is CH4 + 2O2 -> CO2 + 2H2O. If 1 mole of CH4 is completely burned, how many moles of O2 are consumed?

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

27. How many grams of NaCl can be produced from 10 g of Na and 10 g of Cl2 according to the reaction 2Na + Cl2 -> 2NaCl? (Atomic masses: Na=23, Cl=35.5)

A) 10 g B) 16.45 g C) 20 g D) 26.5 g

28. Which law is a direct consequence of Avogadro's hypothesis when dealing with gaseous reactions?

A) Law of Conservation of Mass B) Law of Definite Proportions C) Gay-Lussac's Law of Gaseous Volumes D) Law of Multiple Proportions

29. The term 'stoichiometric amount' refers to the exact molar ratio required for complete reaction according to the balanced chemical equation, meaning there is no:

A) Product B) Reactant left over C) Energy released D) Catalyst needed

30. What is the number of moles in 50 g of CaCO3? (Atomic masses: Ca=40, C=12, O=16)

A) 0.5 moles B) 1 mole C) 2 moles D) 5 moles

31. In the reaction S + O2 -> SO2, if 32 g of sulfur reacts with excess oxygen, what mass of SO2 is produced? (Atomic masses: S=32, O=16)

A) 32 g B) 48 g C) 64 g D) 80 g

32. What is the volume of 2 moles of an ideal gas at STP?

A) 11.2 L B) 22.4 L C) 33.6 L D) 44.8 L

33. The reaction is 2KClO3 -> 2KCl + 3O2. If 1 mole of KClO3 decomposes, how many moles of O2 are produced?

A) 1 mole B) 1.5 moles C) 2 moles D) 3 moles

34. Which law provides the foundation for understanding the composition of compounds at a molecular level?

A) Law of Conservation of Mass B) Law of Multiple Proportions C) Avogadro's Hypothesis D) Law of Definite Proportions

35. If 6 liters of a gas react with 12 liters of another gas to produce 18 liters of a product, this is consistent with which law?

A) Law of Conservation of Mass B) Law of Definite Proportions C) Gay-Lussac's Law of Gaseous Volumes D) Law of Reciprocal Proportions

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

A) 90 g/mol B) 180 g/mol C) 198 g/mol D) 200 g/mol

37. If 100 g of A reacts with B to produce 150 g of product, what is the mass of B that reacted?

A) 50 g B) 100 g C) 150 g D) 250 g

38. The empirical formula of a compound is CH2O. If its molar mass is 180 g/mol, what is its molecular formula?

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

39. A reaction produces 10 g of product. If the percent yield is 50%, what was the theoretical yield?

A) 5 g B) 10 g C) 20 g D) 50 g

40. The law that relates the masses of different elements that combine with the same mass of a third element is:

A) Law of Conservation of Mass B) Law of Definite Proportions C) Law of Multiple Proportions D) Law of Reciprocal Proportions

41. Which of the following is NOT a law of chemical combination?

A) Law of Conservation of Mass B) Law of Definite Proportions C) Dalton's Atomic Theory D) Law of Multiple Proportions

42. What is the number of molecules in 11.2 L of any ideal gas at STP?

A) 3.011 x 10^23 B) 6.022 x 10^23 C) 1.505 x 10^23 D) 1.204 x 10^24

43. Consider the reaction 2H2 + O2 -> 2H2O. If 4 g of H2 react with 32 g of O2, what is the mass of water formed? (Atomic masses: H=1, O=16)

A) 36 g B) 18 g C) 40 g D) 20 g

44. In the reaction 2H2 + O2 -> 2H2O, if 4 g of H2 react with 32 g of O2, which reactant is in excess?

A) Hydrogen B) Oxygen C) Neither D) Cannot be determined

45. Molar volume of a gas at STP is defined as:

A) The volume occupied by 1 mole of gas at 0°C and 1 atm B) The volume occupied by 2 moles of gas at 0°C and 1 atm C) The volume occupied by 1 mole of gas at 25°C and 1 atm D) The volume occupied by 1 mole of gas at 0°C and 2 atm

46. What is the mass of 0.5 moles of Nitrogen gas (N2)? (Atomic mass of N = 14)

A) 7 g B) 14 g C) 28 g D) 35 g

47. The Law of Multiple Proportions was proposed by:

A) John Dalton B) Antoine Lavoisier C) Joseph Proust D) Amedeo Avogadro

48. If 2 liters of CO react with 1 liter of O2 to form 2 liters of CO2 (according to 2CO + O2 -> 2CO2), this illustrates:

A) Law of Conservation of Mass B) Law of Definite Proportions C) Gay-Lussac's Law of Gaseous Volumes D) Law of Multiple Proportions

49. What is the number of moles in 24.5 g of H2SO4? (Atomic masses: H=1, S=32, O=16)

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

50. A reaction has a theoretical yield of 80 g and an actual yield of 60 g. What is the percent yield?

A) 40% B) 60% C) 75% D) 133.3%

Laws of chemical combination and stoichiometry - Online Test

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