JEE Main - Empirical and molecular formula calculations and quantitative analysis basics Online Test (MCQ Quiz)

1. What is the empirical formula of a compound that has the molecular formula C6H12O6?

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

2. A compound has an empirical formula CH2O and a molecular weight of 60 g/mol. What is its molecular formula?

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

3. Which of the following represents the simplest whole-number ratio of atoms of each element present in a compound?

A) Molecular Formula B) Empirical Formula C) Structural Formula D) Condensed Formula

4. If a compound contains 40% carbon, 6.67% hydrogen, and 53.33% oxygen by mass, what is its empirical formula?

A) CH2O B) C2H4O C) C2H4O2 D) CHO

5. A sample of an organic compound has a molar mass of 78 g/mol. If its empirical formula is C2H2, what is its molecular formula?

A) C2H2 B) C4H4 C) C6H6 D) C8H8

6. What is the percentage composition of carbon in methane (CH4)? (Atomic masses: C=12, H=1)

A) 25% B) 75% C) 80% D) 92.3%

7. A compound contains 80% carbon and 20% hydrogen by mass. If its empirical formula is CH3, what is its molecular formula?

A) CH3 B) C2H6 C) C3H9 D) C4H12

8. The empirical formula of glucose is CH2O. What is the ratio of carbon atoms to hydrogen atoms in a glucose molecule?

A) 1:1 B) 1:2 C) 2:1 D) 6:12

9. A compound with the empirical formula C3H8 has a molecular weight of 44 g/mol. What is its molecular formula?

A) C3H8 B) C6H16 C) C9H24 D) C3H4

10. What is the percentage of oxygen by mass in carbon dioxide (CO2)? (Atomic masses: C=12, O=16)

A) 27.27% B) 54.54% C) 72.73% D) 80.00%

11. A compound contains 2.4 g of carbon, 0.4 g of hydrogen, and 3.2 g of oxygen. What is its empirical formula?

A) CH2O B) C2H4O C) C2H4O2 D) CHO

12. If the molecular formula of a compound is twice its empirical formula, what is the ratio of their molecular weights?

A) 1:1 B) 1:2 C) 2:1 D) Cannot be determined

13. A substance has an empirical formula CCl2 and a molecular weight of 147 g/mol. What is its molecular formula? (Atomic masses: C=12, Cl=35.5)

A) CCl2 B) C2Cl4 C) C3Cl6 D) C4Cl8

14. What is the percentage of nitrogen in ammonia (NH3)? (Atomic masses: N=14, H=1)

A) 16.67% B) 46.67% C) 82.35% D) 93.75%

15. A compound has the empirical formula C2H5. If its molecular weight is 58 g/mol, what is its molecular formula?

A) C2H5 B) C4H10 C) C6H15 D) C8H20

16. In quantitative analysis, what is the primary goal of determining the empirical formula?

A) To find the exact number of atoms in a molecule. B) To determine the spatial arrangement of atoms. C) To find the simplest whole-number ratio of elements. D) To calculate the total mass of the compound.

17. A compound contains 50% sulfur and 50% oxygen by mass. What is its empirical formula? (Atomic masses: S=32, O=16)

A) SO B) SO2 C) SO3 D) S2O

18. If the molecular formula of a compound is (CH2O)n, and its molecular weight is 180 g/mol, what is the value of n? (Atomic masses: C=12, H=1, O=16)

A) 1 B) 2 C) 3 D) 6

19. What is the percentage composition of hydrogen in water (H2O)? (Atomic masses: H=1, O=16)

A) 11.11% B) 22.22% C) 33.33% D) 88.89%

20. A compound has an empirical formula C4H4O. If its molecular weight is 136 g/mol, what is its molecular formula?

A) C4H4O B) C8H8O2 C) C12H12O3 D) C16H16O4

21. Which of the following is NOT a step in determining the empirical formula from percentage composition?

A) Convert percentages to grams. B) Convert grams to moles. C) Divide by the largest molar mass. D) Multiply to get whole numbers.

22. A compound contains 3.2 g of sulfur and 4.8 g of oxygen. What is its empirical formula? (Atomic masses: S=32, O=16)

A) SO B) SO2 C) SO3 D) S2O

23. The molecular formula of a compound is C3H6. What is its empirical formula?

A) C3H6 B) C2H4 C) CH2 D) CH

24. What is the percentage by mass of chlorine in carbon tetrachloride (CCl4)? (Atomic masses: C=12, Cl=35.5)

A) 24.24% B) 75.76% C) 80.00% D) 91.43%

25. A compound has an empirical formula C5H10O and a molecular weight of 86 g/mol. What is its molecular formula?

A) C5H10O B) C10H20O2 C) C15H30O3 D) C5H5O

26. If a compound has a molecular formula that is three times its empirical formula, the ratio of their molecular weights is:

A) 1:1 B) 1:3 C) 3:1 D) Cannot be determined

27. A sample of a compound contains 0.5 mol of carbon, 1.0 mol of hydrogen, and 0.25 mol of oxygen. What is its empirical formula?

A) CH2O B) C2H4O C) C2H4O2 D) CHO

28. What is the percentage of potassium in potassium permanganate (KMnO4)? (Atomic masses: K=39, Mn=55, O=16)

A) 15.2% B) 24.7% C) 31.6% D) 45.8%

29. A compound has an empirical formula CH. If its molecular weight is 26 g/mol, what is its molecular formula?

A) CH B) C2H2 C) C3H3 D) C4H4

30. In the combustion analysis of an organic compound, what is typically collected and measured to determine the amount of carbon?

A) Water (H2O) B) Carbon Dioxide (CO2) C) Sulfur Dioxide (SO2) D) Nitrogen Gas (N2)

31. A compound contains 88.8% carbon and 11.2% hydrogen by mass. What is its empirical formula? (Atomic masses: C=12, H=1)

A) CH B) CH2 C) C2H3 D) C3H4

32. What is the empirical formula of a compound with the molecular formula C6H6?

A) C6H6 B) C3H3 C) C2H2 D) CH

33. A compound has the empirical formula C2H6O and a molecular weight of 46 g/mol. What is its molecular formula?

A) C2H6O B) C4H12O2 C) C6H18O3 D) CH3OH

34. What is the percentage of sulfur in sulfuric acid (H2SO4)? (Atomic masses: H=1, S=32, O=16)

A) 9.8% B) 32.7% C) 65.3% D) 70.0%

35. A compound contains 40.0% carbon, 6.7% hydrogen, and 53.3% oxygen by mass. Its molecular weight is 180 g/mol. What is its molecular formula?

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

36. If the empirical formula is CH2 and the molecular formula is C3H6, what is the factor 'n' in the molecular formula (Empirical Formula)n?

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

37. What is the percentage composition of oxygen in ozone (O3)? (Atomic mass: O=16)

A) 33.33% B) 66.67% C) 100% D) 0%

38. A compound contains 75% carbon and 25% hydrogen by mass. What is its empirical formula? (Atomic masses: C=12, H=1)

A) CH B) CH2 C) CH3 D) C2H3

39. The empirical formula of a compound is C3H4O2. If its molecular weight is 72 g/mol, what is its molecular formula?

A) C3H4O2 B) C6H8O4 C) C9H12O6 D) C3H8O2

40. In the determination of the empirical formula, if the mole ratios are 0.5 : 1 : 0.25, what is the simplest whole-number ratio?

A) 1:2:1 B) 2:4:1 C) 4:2:1 D) 1:1:2

41. What is the percentage of nitrogen in ammonium nitrate (NH4NO3)? (Atomic masses: N=14, H=1, O=16)

A) 17.5% B) 35.0% C) 52.5% D) 70.0%

42. A compound has the empirical formula C4H8O2 and a molecular weight of 144 g/mol. What is its molecular formula?

A) C4H8O2 B) C8H16O4 C) C12H24O6 D) C4H4O2

43. What is the empirical formula of a compound containing 60% carbon, 8% hydrogen, and 32% oxygen by mass? (Atomic masses: C=12, H=1, O=16)

A) C2H3O B) C3H4O C) C3H4O2 D) C6H8O2

44. If the molecular formula of a compound is C4H10, what is its empirical formula?

A) C4H10 B) C2H5 C) CH D) C4H5

45. What is the percentage of hydrogen in ethane (C2H6)? (Atomic masses: C=12, H=1)

A) 16.67% B) 25.00% C) 75.00% D) 83.33%

46. A compound has an empirical formula C5H12. If its molecular weight is 72 g/mol, what is its molecular formula?

A) C5H12 B) C10H24 C) C15H36 D) C2H5

47. The combustion of 0.1 mol of an organic compound yields 0.3 mol of CO2 and 0.4 mol of H2O. What is the empirical formula of the compound?

A) CH2 B) C3H4 C) C3H8 D) C3H4O

48. What is the percentage composition of phosphorus in phosphoric acid (H3PO4)? (Atomic masses: H=1, P=31, O=16)

A) 9.75% B) 18.9% C) 31.6% D) 42.1%

49. A compound contains 30.43% nitrogen and 69.57% oxygen by mass. What is its empirical formula? (Atomic masses: N=14, O=16)

A) NO B) NO2 C) N2O D) N2O4

50. If a compound's molecular formula is three times its empirical formula, the ratio of their molecular weights is:

A) 1:1 B) 1:3 C) 3:1 D) Cannot be determined

Empirical and molecular formula calculations and quantitative analysis basics - Online Test

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