NSMQ 2024 CHEMISTRY PAST QUESTIONS AND ANSWERS.

PREAMBLE: Arrange the following elements in order of increasing electronegativity.

1. Na, Li, Rb

Ans: Rb < Na < Li

2. F, Br, Cl

Ans: Br < Cl < F

3. Si, Al, P

Ans: Al < Si < P

4. Mg, Sr, Be

Ans: Sr < Mg < Be

5. Calculate the percentage by mass of nitrogen in H₂O

Ans: 63.6% ≈ 64%

6. Calculate the percentage by mass of nitrogen in CH₂N

Ans: 50%

7. Calculate the percentage by mass of oxygen in NO₂

Ans: 70%

8. Calculate the percentage by mass of oxygen in N₂O₃

Ans: 63%

9. Give the name of one element in period 2 that has only one letter as symbol

Ans:

• Fluorine
• Nitrogen
• Carbon
• Boron

PREAMBLE: Name the major inter-unit forces present in the given molecules or compound

10. Neon gas

Ans: Induce dipole-induce dipole/Van Der Waal

11. Solid magnesium chloride

Ans: Electrostatic force

12. Liquid methanol

Ans: Dipole dipole

13. Propane gas

Ans: Van Der Waal

14. Give the name of one family of organic compound with the only single bond in its functional group

Ans:

• Amide
• Alcohol
• Ether
• Alkane

Arrange the given element in order of increasing first ionization energy

15. O, Li, C

Ans: Li, C, O

16. Si, Na, S

Ans: Na, Si, S

17. Ba, Be, Ca

Ans: Ba, Ca, Be

18. B, Al, Ga

Ans: Ga, Al, B

PREAMBLE: Arrange the following in order of increasing atomic radius

19. Na, Be, Ne

Ans: Ne, Be, Na

20. Be, K, Cs

Ans: Be, K, Cs

21. C, Si, Cl

Ans: C, Cl, Si

22. Al, P, Ar

Ans: Ar, P, Al

23. Ca, Ba, Br

Ans: Br, Ca, Ba

24. Give one intensive property of water at room temperature

Ans:

• Boiling point
• Density
• Colour
• Vapour pressure
• Viscosity
• Surface tension
• Refractive index

PREAMBLE: Indicate which is more abundant in the human body

25. Zinc, sodium, chromium

Ans: Sodium

26. Phosphorus, iodine, argon

Ans: Phosphorus

27. Chlorine, silicon, iodine

Ans: Chlorine

28. Magnesium, potassium, molybdenum

Ans: Potassium

29. How many moles of Na₂O are present in a 3.1g sample

Ans: 0.050moles

30. How many moles of Na₂CO₃ are present in 5.3g sample

Ans: 0.050moles

31. How many moles of K₂O are present in a 1.88 g sample

Ans: 0.0050moles

32. How many moles of K₂CO₃ are present in 1.38g sample

Ans: 1.00 × 10^-2 moles

PREAMBLE: Give the formula of the salt formed given methathesis reaction

33. CH + FeSO₄

Ans : COSO₄

34. Mg + AgNO₃

Ans :(MgNO)₃

35. NH₃ + CHSO₄

Ans :(NH₄)₂SO₄

36. Al + H₃PO₄

Ans: AlPO₄

37. Ba + H₂C₂O₄

Ans: BaC₂O₄

38. Give the systematic name of one possible isomer of the saturated hydrocarbon with 6 carbon atoms.

Ans:

• 2-methyl pentane
• 3-methyl pentane
• 2,2-dimethyl butane
• 2, 3-dimethyl butane

PREAMBLE: The reaction HF + H₂O → F^– + H₃O⁺ is an acid base reaction

39. Based on the forward reaction, identify the acid

Ans: H₃

40. Based on the backward reaction identify the acid

Ans: H₃O⁺

41. Based on the backward reaction identify the base

Ans: F^–

42. Which of the species in the reaction cannot act as a Bronsted-lowry acid

Ans: F^–

43. An organic compound has only one oxygen atom in addition to carbon and hydrogen atoms, give the name of one class of compounds to which the compound may belong

Ans:

• Alkanol
• Ether
• Alkanols
• Phenol

44. Calculate the time it takes for a radioactive particle to decay 100g to 6.25g given that it has a half-life of 3.50 hours

Ans: 14.0 hours

45. Calculate the percentage by mass of oxygen in calcium carbonate

Ans: 48%

46. A compound is represented by CₓHᵧO. What are the values of x, y, and z if it’s the 4th member of the homogeneous series of alcohol

Ans: x = 4, y = 10, and z = 1

47. Calculate the mass of X₂O₃ present in 250cm³ of 0.400mol/dm³ solution [X=27.0g/mol]

Ans: 10.2g

48. Calculate the mass of R₃N present in 500cm³ of 0.300mol/dm³ solution [R=7.00g/mol]

Ans: 5.25g

49. What mass of TBr₂ is present in 300cm³ of 0.25mol/dm³ solution [T=24g/mol]

Ans: 13.8g

50. Calculate the mass of Y₂O present in 200cm³ of 0.15mol/dm³ solution [Y=23g/mol]

Ans: 1.86g

PREAMBLE: Provide answers to the following with regard to the periodic table

51. What is the most reactive metal on the periodic table.

Ans: Francium (Fr)

52. What is the most reactive non-metal found on earth

Ans: Fluorine (F₂)

53. What is the element with the largest atomic size

Ans: Francium (Fr)

54. What is the element with strongest electron affinity

Ans: Chlorine (Cl)

55. The compound with molecular formula C₅H₁₂O₂ is a diol (two –OH groups), with only one methyl group, and the hydroxyl groups are not on the same carbon. Give two possible isomers of the compound;

Ans:

• 2-Methyl-1,2-butanediol
• 2-Methyl-1,3-butanediol
• 2-Methyl-1,4-butanediol
• 3-Methyl-1,2-butanediol
• 3-Methyl-1,3-butanediol

56. Oxygen effuses 3 time faster than a compound T₂ What is the atomic mass of element T

Ans: 136g/mol

57. In a titration of Na₂CO₃ against dilute HCl, using methyl orange as indicator, 20.0 cm³ of the base required 24.0 cm³ of 0.10 mol/dm³ HCl. Calculate the concentration of the base.

Ans: 0.060 mol/dm³

58. Borax is a mineral containing boron and has the molecular formula Na₂B4O₇10H₂O. What is the percentage of oxygen (O) in borax, rounded to three significant figures? Take [B=10.0, Na =23.0, O=16.0, and H=1.00]

Ans: 72.0%

59. Dolomite is an ore of calcium and has the formular CaMg(CO₃)₂. What is the Percent Mg in Dolomite to three significant figures. [Ca=40.0, Mg=24.0, and O=16.0]

Ans: 13.0%

60. Cryolite is a mineral with the chemical formula Na₂AlF₆. What is the percentage by mass of sodium (Na) in cryolite to three significant figures [Al=27.0, Na= 23.0, F=19.0]

Ans: 32.9%

61. The mineral (MgFe)₂SiO₄ is a solid solution. What is the percentage by mass of iron (Fe) to three significant figures? [Mg=24.0, Fe=56.0, Si=28.0, and O=16.0]

Ans: 54.9%

Balance the following redox reactions in basic medium

62. Ag_(s) + CrO₄²⁻_(aq) → Ag⁺_(aq) + Cr(OH)₃_(s)

Ans: 3Ag_(s) + CrO₄²⁻_(aq) + 4H₂O_(l) → 3Ag⁺_(aq) + Cr(OH)₃_(s) + 5OH⁻_(aq)

63. ClO₂_(aq) → ClO₃⁻_(aq) + Cl⁻_(aq)

Ans: 6ClO₂(aq) + 6OH⁻(aq) → 5ClO₃⁻(aq) + Cl⁻(aq) + 3H₂O(l)

64. Fe(OH)₃_(s) + OCl⁻_(aq) → FeO₄²⁻_(aq) + Cl⁻_(aq)

Ans: 2Fe(OH)₃_(s) + 3OCl⁻_(aq) + 4OH⁻_(aq) → 2FeO₄²⁻_(aq) + 3Cl⁻_(aq) + 5H₂O_(l)

65. MnO₂_(s) + ClO₃⁻_(aq) → MnO₄⁻_(aq) + Cl⁻_(aq)

Ans: 2MnO₂_(s) + ClO₃⁻_(aq) + 2OH⁻_(aq) → 2MnO₄⁻_(aq) + Cl⁻_(aq) + H₂O_(l)

66. A hydrocarbon chain consists of five carbon atoms, with a single double bond between the second and third carbons. Additionally, a methyl group (-CH₃) is attached to the fourth carbon. What is the correct IUPAC name for this compound?

Ans: 4-Methylpent-2-ene

67. A six-carbon chain contains a single triple bond between the first and second carbons. There is also a chlorine (-Cl) substituent attached to the third carbon and a hydroxyl (-OH) group on the fifth carbon. What is the correct IUPAC name for this compound?

Ans: 3-Chloro-1-hexyn-5-ol or 4-chloro-5-hexyn-2-ol

68. A three-carbon chain contains a hydroxyl (-OH) group on the second carbon and a carboxyl (- COOH) group on the first carbon. What is the correct IUPAC name for this compound?

Ans: 2-Hydroxypropanoic acid (Lactic acid)

69. A benzene ring has two substituents: a nitro group (-NO₂) on the first carbon and a bromine (-Br) atom on the third carbon. What is the correct IUPAC name for this compound?

Ans: 3-Bromonitrobenzene

Preamble: Two sparingly soluble salts, XY and ZY, dissolve in water to produce their respective ions. Ksp (XY) = 3.12 × 10^-11 and Ksp (ZY) = 6.48 × 10^-13. Initially, the solution contains only XY dissolved at its saturation point (i.e., fully saturated), and no added Y⁻ from any external source.

70. Calculate the initial concentrations of X⁺ and Y^– in a saturated solution of XY.

Ans: 5.58 × 10⁻⁶moldm^-3

71. A small amount of solid ZY is added to the solution containing saturated XY, but no precipitation is observed. What is the maximum concentration of Z⁺ that can exist in the solution without causing any precipitation of ZY?

Ans: 1.16 × 10⁻⁷moldm^-3

72. As Y⁻ increases (due to ZY being added or other sources), ZY begins to precipitate when [Y^–] = 1.20 × 10^-4 moldm^-3. At this point, what is the concentration of X⁺ remaining in solution?

Ans: 2.60 × 10⁻⁷moldm^-3

73. Calculate the percentage of XY still dissolved compared to its original saturated concentration when ZY begins to precipitate.

Ans: 4.66%

Preamble: Give the shape of the following molecules

74. SF₆

Ans: Octahedral

75. XeF₂

Ans: Linear

76. ICl_4-

Ans: Square planar

77. BrF₃

Ans: T-shaped

78. Calculate the volume in cm³ of 16.0moldm^-3 ethanoic acid needed to prepare 5.00 x 10²cm³ of 2.50 moldm^-3 solution of the acid.

Ans: 78.1cm³

79. Calculate the mass in grams of ethanedioic acid dihydrate needed to prepare 200.0cm³ of 0.700 moldm^-3

Ans: 17.6 g

80. Calculate the final concentration of HCl in moldm^-3 when 150.0 cm³ of 6.00moldm^-3 HCl are diluted with 250.0 cm³ of de-ionized water and 100.0cm³ of this solution, further diluted to 300.0 cm³.

Ans: 0.750M

81. Calculate the volume in cm³ of 12.0mol/dm³ nitric acid (HNO₃) needed to prepare 2.50 x 102cm³ of a 1.50 mol/dm³ solution.

Ans: 31.3cm³

82. Calculate the concentration of an aqueous KCl solution if 20.0 cm³ of this solution gives 0.287 g of AgCl when treated with excess AgNO₃ solution. Ag = 108.0; Cl = 35.5

Ans: 0.100M

83. Calculate the concentration of sodium hydroxide if 12.0 cm³ of NaOH is needed to neutralize 20.0 cm³ of 0.15 moldm⁻³ ethanedioic acid (oxalic acid). Give your answer to 2 places of decimal

Ans: 0.50M

84. Calculate the volume of 0.049 moldm⁻³ H₂SO₄ needed to neutralize 14.0 cm³ of 0.10 moldm⁻³ aqueous ammonia solution. Give your answer to one place of decimal.

Ans: 14.3 cm³

85. Calculate the concentration of an aqueous Na₂SO₄ solution if 25.0 cm³ of this solution gives 0.466 g of BaSO₄ when treated with excess BaCl₂ solution. Ba = 137, S = 32.0, O = 16.0

Ans: 0.0800M

86. Give the name and formula of one ore of iron

Ans:

• Haematite: Fe₂O₃
• Limonite: Fe₂O₃.H₂O
• Magnetite (or lodestone): Fe₃O₄
• Siderite (or sphatic iron ore): FeCO₃
• Iron pyrites: FeS₂

87. An electron is located in the 2s orbital. Give a complete set of quantum numbers for this electron assuming it spins up.

Ans: 2, 0, 0, +%

88. Give a complete set of quantum numbers for the last electron that enters the 4p orbital

Ans: 2,1, +1, -1/2

89. The compound C5H12O2 is a diol, with -OH groups on terminal carbons. Each should give a possible isomer of it.

Ans:

• 1,5-Pentanediol
• 2- Methyl-1,4-butanediol
• 3-Methyl-1,4-butanediol
• 2,2-Dimethylpropane-1,3-diol

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