1. How is mass concentration calculated?

A. \( \text{Mass conc.} = \frac{\text{mass (g)}}{\text{volume (dm}^3)} \) B. \( \text{Mass conc.} = \frac{\text{volume (dm}^3)}{\text{mass (g)}} \) C. \( \text{Mass conc.} = \text{mass} \times \text{volume} \) D. \( \text{Mass conc.} = \text{mass} + \text{volume} \)

2. What mass concentration corresponds to 4 g of NaOH dissolved in 100 ml of water?

A. 4 g/dm³ B. 40 g/dm³ C. 400 g/dm³ D. 0.4 g/dm³

3. Which of the following describes a net forward chemical reaction?

A. \( \Rightarrow \) B. \( \leftrightarrow \) C. \( \leftrightarrows \) D. \( ⇌ \)

4. If 40 g of NaOH dissolved in 1 dm³ gives 1 mol/dm³ solution, what is the relative molecular mass (RMM) of NaOH?

A. 20 B. 23 C. 40 D. 17

5. Which is NOT a step involved in balancing a chemical equation?

A. Counting atoms on each side B. Changing coefficients to balance atoms C. Changing subscripts to balance atoms D. Repeating the process until balanced

6. What moles of Na₂CO₃ are present when 0.52 g of it is dissolved, given its relative molecular mass (R.M.M) is approximately 106?

A. 0.0049 mol B. 0.49 mol C. 0.052 mol D. 4.9 mol

7. What is the physical meaning of the coefficient in a balanced chemical equation, such as the 2 in 2H₂O?

A. Number of molecules or moles involved B. Number of atoms in a molecule C. Physical state of the chemical D. Electrical charge on the molecule

8. What does a balanced chemical equation ensure in a chemical reaction?

A. The same number of molecules on both sides B. The same mass and number of atoms on both sides C. The reaction only proceeds in one direction D. The products are always in liquid state

9. When balancing chemical equations, which of the following must remain unchanged?

A. The coefficient B. The subscript in chemical formulas C. The number of molecules D. The volume

10. What is the relative molecular mass (RMM) of carbon dioxide, \(CO_2\)?

A. 44 B. 46 C. 22 D. 12

11. Which principle explains why the number of atoms must be the same on both sides of a chemical equation?

A. Law of definite proportions B. Law of conservation of mass C. Law of multiple proportions D. Law of chemical equilibrium

12. How is molar concentration defined?

A. Mass of solute per volume of solution in g/dm³ B. Number of moles of solute per volume of solution in dm³ C. Number of atoms in a molecule D. Volume of solute per mass of solvent

13. When converting 100 ml to dm³, what volume in dm³ is used for molar concentration calculations?

A. 10 dm³ B. 0.01 dm³ C. 0.1 dm³ D. 1 dm³

14. What unit is commonly used for molar concentration?

A. g/ml B. mol/dm³ C. g/dm³ D. mol/Liter²

15. Which symbol in a chemical equation denotes an aqueous solution?

A. (s) B. (l) C. (g) D. (aq)

16. What does the subscript in a chemical formula indicate?

A. The number of molecules B. The number of atoms of a given element in one molecule C. The charge on the atom D. The physical state of the substance

17. What information do coefficients in a balanced chemical equation provide?

A. Number of atoms per molecule B. Number of moles of reactants and products C. Atomic number of elements D. Mass of substances

18. If 25 ml of Na₂CO₃ stock solution is titrated and requires 20 ml of HCl, which of the following can be calculated from this data?

A. The molar mass of Na₂CO₃ B. The physical state of HCl C. The molarity of HCl and Na₂CO₃ D. The volume of distilled water used

19. In a chemical equation, what does the arrow (→) denote?

A. Chemical equilibrium B. Net forward reaction C. Stoichiometric ratio D. Reversible reaction

20. What is stoichiometry?

A. Study of atomic structure B. Qualitative relation between reactants C. Quantitative relation between moles and mass of reactants and products D. Measurement of temperature change in reactions

21. Which of the following correctly denotes an aqueous solution in a chemical equation?

A. (g) B. (s) C. (aq) D. (l)

22. What is the mass of \(HgS\) formed when 2.00 g of \(Hg(NO_3)_2\) reacts, given molar masses 324.6 for \(Hg(NO_3)_2\) and 232 for \(HgS\)?

A. 1.00 g B. 1.43 g C. 2.00 g D. 0.75 g

23. In a titration experiment, what does the average titre value represent?

A. Volume of titrant required to completely react with the analyte B. Mass of the analyte in the solution C. Molarity of the unknown solution D. Volume of distilled water used in dilution

24. What does the subscript represent in a chemical formula like \(O_2\)?

A. Number of molecules B. Number of atoms of that element in one molecule C. Ionic charge D. Number of moles

25. How many moles of oxygen (\(O_2\)) are needed to completely burn 1 mole of pentanol (\(C_5H_{12}OH\)) in the reaction \(2C_5H_{12}OH + 15O_2 → 10CO_2 + 12H_2O\)?

A. 7.5 moles B. 15 moles C. 30 moles D. 5 moles

26. What do the symbols (s), (l), (g), and (aq) represent in chemical equations?

A. States of matter: solid, liquid, gas, and aqueous solution respectively B. Different reaction types C. Atomic numbers D. Types of ions

27. Which symbol describes an equilibrium reaction in a chemical equation?

A. → B. ⇌ C. = D. ⇄

28. How many grams of CO₂ are produced for each mole of alkanol burned in the equation 2C₅H₁₂OH + 15O₂ → 10CO₂ + 12H₂O?

A. 22 g B. 44 g C. 220 g D. 110 g

29. How many grams of \(CO_2\) are produced from burning 1 mole of pentanol in the reaction \(2C_5H_{12}OH + 15O_2 → 10CO_2 + 12H_2O\)? (Molar mass of CO₂ = 44)

A. 44 g B. 220 g C. 88 g D. 110 g

30. What is the formula for molar concentration?

A. \( \text{Molar conc.} = \frac{\text{mass concentration}}{\text{RMM}} \) B. \( \text{Molar conc.} = \frac{\text{volume}}{\text{mass}} \) C. \( \text{Molar conc.} = \text{mass} \times \text{volume} \) D. \( \text{Molar conc.} = \frac{\text{moles}}{\text{mass}} \)

31. What is the molarity of a solution prepared by dissolving 0.52 g of \(Na_2CO_3\) in 100 mL of distilled water? (RMM of \(Na_2CO_3\) = 106)

A. 0.005 mol/dm³ B. 0.049 mol/dm³ C. 0.52 mol/dm³ D. 0.49 mol/dm³

32. What does the law of conservation of mass state?

A. Mass is created during reactions B. Mass is destroyed during reactions C. Matter cannot be created or destroyed in a chemical reaction D. Mass changes to energy in reactions

33. How can you balance a chemical equation?

A. By changing chemical formulas B. By changing coefficients to have the same number of atoms on both sides C. By changing subscripts D. By adding new reactants

34. Which formula correctly represents the molar concentration given mass concentration and RMM?

A. \( M = \frac{\text{mass concentration}}{\text{RMM}} \) B. \( M = \text{mass concentration} \times \text{RMM} \) C. \( M = \frac{\text{RMM}}{\text{mass concentration}} \) D. \( M = \text{mass concentration} + \text{RMM} \)

35. Which of the following is TRUE about chemical equations?

A. They represent only the physical state of reactants B. They must be balanced to obey the conservation of mass C. They show the temperature and pressure changes in reactions D. They only represent gaseous reactions

36. When calculating molar concentration from mass concentration, which information is NOT required?

A. The volume of the solution B. The relative molecular mass of the solute C. The mass concentration in g/dm³ D. The color of the solution

37. What does a chemical equation represent?

A. A list of elements in a reaction B. A symbolic representation of a chemical reaction showing reactants and products C. The mass of reactants only D. The temperature at which a reaction occurs

38. In the reaction Hg(NO₃)₂ + Na₂S → HgS + 2NaNO₃, if 2.00 g of Hg(NO₃)₂ reacted, what is the mole ratio between Hg(NO₃)₂ and HgS?

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

39. Which symbol is used to represent a chemical reaction occurring in both the forward and backward directions?

A. → B. ⇌ C. = D. ⇄

40. If 4 moles of NH₃ react with 3 moles of O₂, how many moles of water (H₂O) are produced?

A. 4 B. 3 C. 2 D. 6

41. Which of the following best describes stoichiometry?

A. The study of chemical symbols B. The quantitative relationship between moles and masses of reactants and products C. The balancing method of chemical equations D. The physical states of reactants in a reaction

42. Which of these chemical equation symbols is used to denote stoichiometric relationships?

A. → B. ⇌ C. = D. ⇄

43. If 25 mL of the above stock solution (0.049 mol/dm³) is titrated, how many moles of \(Na_2CO_3\) are in the 25 mL aliquot?

A. 0.00123 mol B. 0.001225 mol C. 0.0123 mol D. 0.00049 mol

44. If 0.588 moles of NH₃ react, how many moles of O₂ are consumed according to the equation \(4NH_3 + 3O_2 \to \ldots\)?

A. 0.441 mol B. 0.784 mol C. 0.294 mol D. 0.588 mol

45. Which of these represents a balanced chemical equation for hydrogen and oxygen forming water?

A. H₂ + O₂ → H₂O B. 2H₂ + O₂ → 2H₂O C. 2H + 2O → 2H₂O D. H + O₂ → H₂O

46. In the molar concentration formula, how is molar concentration calculated from mass concentration?

A. Mass concentration multiplied by relative molecular mass B. Mass concentration divided by relative molecular mass C. Relative molecular mass divided by mass concentration D. Mass concentration added to relative molecular mass

47. What is the mole ratio coefficient for oxygen in the reaction \( 4NH_3 + 3O_2 \to 2N_2 + 6H_2O \)?

A. 2 B. 3 C. 4 D. 6

48. What state does the symbol (g) represent in a chemical equation?

A. Solid B. Gas C. Liquid D. Aqueous

49. What is the mass concentration of 4 g NaOH dissolved in 100 ml of water?

A. 4 g/dm³ B. 10 g/dm³ C. 40 g/dm³ D. 400 g/dm³

50. What is the number of moles for 10 g of NH₃ where RMM = 17?

A. 0.58 mol B. 0.59 mol C. 0.588 mol D. 0.6 mol