Anglo-Chinese School (Independent)

Singapore Junior Chemistry Olympiad Training

Name: Date:

Class: Score: /30

Quiz 1
Duration: 30 minutes
Each question is worth 1 mark.
Write your answers in the table below.

1 2 3 4 5 6 7 8 9 10

11 12 13 14 15 16 17 18 19 20

21 22 23 24 25 26 27 28 29 30

1. Find the value of a.

C3H7OH (l) + a O2 (g) → b CO2 (g) + c H2O (l)

A. 2.5 B. 4.5 C. 5 D. 9

2. A 0.20 M solution of K2CO3 was neutralized completely by 30 cm3 of a 0.40 M solution of HNO3. The
resulting solution of KNO3was evaporated until 50% of the original volume remained.

What is the final volume and concentration of the KNO3 solution?

A. 30 cm3, 0.40 M B. 30 cm3, 0.80 M C. 45 cm3, 0.40 M D. 45 cm3, 0.80 M

3. Which gas behaves most closely to that of an ideal gas?

A. C3H6 B. F2 C. HCl D. NO2

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4. The plots of PV/RT against P for 1 mol ideal gas and 1 mol SO2 at 300K are given below:

Which graph shows how 1 mol CO2 behaves at 300K?

A. B.

C. D.

5. Which of the following is not a plausible ground state electronic configuration of V x+ where Vx+ is an ion
of vanadium?

[Ar] denotes 1s2 2s2 2p6 3s2 3p6.

A. [Ar] 4s2 B. [Ar] 3d3 C. [Ar] 3d1 D. [Ar]

6. Which element, in the ground state, has the most number of unpaired electrons?

A. Nitrogen B. Phosphorous C. Chromium D. Manganese

7. Which element is able to form the most number of noble gas compounds?

A. Neon B. Argon C. Krypton D. Xenon

8. Which statement(s) concerning periodic trends is/are correct?

I The electronegativity of elements increases across a period.

II The electronegativity of elements increases down a group.
III The oxides of elements change from acidic to basic across a period.

A. I only B. I and II only C. I and III only D. I, II and III

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9. The first electron affinity of oxygen is associated with an enthalpy change of ΔH = −142 kJ mol-1.

What are the correct descriptions for the second electron affinity of oxygen regarding its sign and
absolute value compared to its first electron affinity?

A. Negative, much greater absolute value B. Negative, slightly greater absolute value
C. Positive, much greater absolute value D. Positive, slightly greater absolute value

10. Which statement(s) concerning the electrical conductivity of sodium chloride is/are correct?

I Sodium chloride conducts electricity in the aqueous state.

II Sodium chloride conducts electricity in the molten state.
III Sodium chloride conducts electricity in the solid state.

A. I only B. I and II only C. I and III only D. I, II and III

11. Which is soluble in an organic solvent?

A. Diamond B. Fullerene C. Graphite D. Quartz

12. 11.9 g grams of cobalt (II) carbonate reacted with oxygen on strong heating to form 8.30 g of its oxide.
What is the oxidation state of cobalt after the reaction?

A. 0 B. +1 C. +2 D. +3

13. 20 cm3 of 0.1 M aqueous sodium thiosulfate (Na2S2O3) reacts completely with 40 cm3 of 0.2 M aqueous
sodium hypochlorite (NaClO).

Given that the hypochlorite ions are reduced to chloride ions, what is the sulfur containing species at the
end of the reaction?

A. SO2 B. SO32− C. SO42− D. S4O62−

14. If solid manganese is added to an acidified solution of potassium dichromate, which species will be
present after both reagents have reacted completely?

The following half equations may be relevant to the above reaction:

Half Equation Eo / V
Mn (aq) + 2e− ⇌ Mn (s)
2+
−1.19
MnO2 (s) + 4H+ (aq) + 2e− ⇌ Mn2+ (aq) + 2H2O (l) +1.23
MnO4− (aq) + 4H+ (aq) + 3e− ⇌ MnO2 (s) + 2H2O (l) +1.70
Cr3+ (aq) + 3e− ⇌ Cr (s) −0.74
Cr2O7 (aq) + 14H+ (aq) + 6e− ⇌ 2Cr3+ (aq) + 7H2O (l)
2−
+1.33

A. Mn (s) and Cr2O72− (aq) B. Mn2+ (aq) and Cr3+ (aq)

C. MnO2 (s) and Cr3+ (aq) D. MnO2 (s) and Cr (s)

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15. Based on the following reaction:

N2 (g) + 3H2 (g) → 2NH3 (g) ΔHr = −92 kJ mol-1

deduce the N≡N bond enthalpy for the given the following average bond enthalpies:

H−H ΔH = 436 kJ mol-1 N−H ΔH = 391 kJ mol-1

A. 431 kJ mol-1 B. 649 kJ mol-1 C. 896 kJ mol-1 D. 946 kJ mol-1

16. Instant cold packs are activated by allowing two substances to mix together. What are the signs of ΔG
(Gibbs free energy), ΔH (enthalpy) and ΔS (entropy) in the reaction in the cold pack respectively?

A. −, −, + B. −, +, + C. +, −, + D. +, +, −

17. A car engine consumes pure octane at a rate of 9.8 cm3/s during peak performance. The density of octane
is 0.70 g/cm3 and its enthalpy of combustion is -5000 kJ/mol. What is the theoretical power output of the
engine, given that 1 hp = 750 J/s?

A. 400 hp B. 610 hp C. 820 hp D. 1030 hp

18. The following graph shows how the concentration of MnO4− changes with time in the reaction between
KMnO4 and H2C2O4:

What can be deduced from this graph?

A. A catalyst is initially present.

B. The reaction is highly exothermic hence the sharp decrease in [MnO4−].
C. The reaction is first order with respect to MnO4−.
D. The reaction autocatalytic (produces its own catalyst).

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19. The time taken for reactants A, B and C to produce a given amount of products, when A, B and C had
differing concentrations, were recorded in the table below.

Experiment [A] / mol dm-3 [B] / mol dm-3 [C] / mol dm-3 Time taken / s
1 1.0 1.0 1.0 60
2 1.0 2.0 1.0 15
3 1.0 1.0 2.0 30
4 2.0 2.0 2.0 15

What is the overall order of reaction?

A. 0 B. 1 C. 2 D. 3

20. Which of the following is/are considered as a weak acid?

I HF
II HCl
III HBr

A. I only B. I and II only C. I and III only D. I, II and III

21. In a conductometric titration, aqueous Ba(OH)2 was added to a solution of HCl. Which graph correctly
shows the conductance of the solution throughout the whole experiment?

A. B.

C. D.

22. Taking the first dissociation of sulfuric acid to be complete, and the second to have a Ka value of 1.26 ×
10-2, what is the pH of 2.00 M sulfuric acid?

A. −0.151 B. −0.301 C. −0.304 D. −0.602

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23. Thymolphthalein is an acid base indicator which transitions from colorless to blue as pH increases. At
the endpoint of a titration, 42.5% of the indicator molecules must be blue for the color change to be
visible. Given that the pKb of thymolphthalein is 4.25, find the pH of the solution at endpoint.

A. 4.12 B. 4.38 C. 9.62 D. 9.88

24. When propanol undergoes an esterification reaction with propanoic acid, what is the number of possible
isomers?

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

25. Organic molecule A does not react with potassium permanganate. Which class of organic compounds
does molecule A not belong to?

A. Alcohol B. Aldehyde C. Alkane D. Alkene

26. Hydroprene is a juvenile hormone analog commonly used as an insecticide. The diagram below shows
the structure of the molecule.

H H
H3C O

CH3 CH3 H CH3 O

CH3

What is the total number of stereoisomers of this molecule?

A. 2 B. 4 C. 8 D. 16

27. Acetaminophen (paracetamol) is a widely used medication for pain relief. The structure of
acetaminophen is shown below:

NH CH 3

O
HO

Which of the following statements concerning acetaminophen is false?

A. Acetaminophen is amphipathic.
B. Acetaminophen can react with both acids and bases.
C. A "silver mirror" is observed when Tollen's reagent is added to a sample of acetaminophen.
D. It is impossible for acetaminophen to have a stereoisomer.

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28. Which statement does not explain why ring structure 1 is a better representation of benzene than ring
structure 2?

Structure 1 Structure 2

A. Benzene is unable to decolorize aqueous bromine.

B. Benzene has delocalized electrons but is an insulator of electricity.
C. C−C and C=C bonds differ in length, but all bond lengths in benzene are the same.
D. The hydrogenation of benzene releases more energy than expected.

29. If a nitrile X is hydrolyzed in acidic conditions, it yields the same product as alcohol Y when completely
oxidized. Which option correctly identifies molecules X and Y respectively?

A. C6H5CN and C6H5OH B. C6H5CH2CN and C6H5CH2CH2OH

C. CH3CH3CH2CN and CH3CH3CH2OH D. CH3CH3CH2CN and CH3CH2CH(OH)CH3

30. Paper chromatography is performed on ink from a pen using a non-polar solvent. The stationary phase is
shown below:

It is given that royal blue is the most polar solute while yellow is the most non-polar solute. Which of the
following would reverse the order in which the solutes appear?

A. Using paper that royal blue and yellow binds better to than orange and light blue.
B. Changing the stationary phase to one that interacts better with all of the solutes.
C. Using a polar solvent instead of a non-polar solvent.
D. It is not possible.

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