Sample Questions for the Rhode Island High School Chemistry Contest

Instructors have frequently asked for sample questions or old exams to get the flavor of future exams. This page provides some sample questions. Clicking on the "Explanation" provides the correct answer and a brief explanation to the question.

1. How many significant figures are there in the measured number 0.0000730500?

A. 3
B. 4
C. 6
D. 8
E. 11

Explanation

2. The formula for hypochlorous acid is

A. HCl
B. HClO
C. HClO2
D. HClO3
E. HClO4

Explanation

3. "Amorphous" refers to

A. a lover's quarrel.
B. something that can act as an acid or a base.
C. one of three types of calcination that can be performed in a vacuum.
D. a material that is combined with mercury.
E. something lacking definite crystalline structure.

Explanation

4. What is the pH of a 1.0×10–10 M aqueous solution of hydrochloric acid?

A. –10.0
B. 1.0
C. 7.0
D. 10.0
E. 14.0

Explanation

5. All other things being equal, which of the following acids would be the best choice for making a buffer for pH = 4.26?

A. Formic acid, molar mass = 46.03
B. Butanoic acid, melting point = –4.26 °C
C. Acetoacetic acid, Ka = 2.62×10–4
D. Ethylphenylacetic acid, Ka = 4.27×10–5
E. m-Chlorocinnamic acid, Ka = 5.13×10–5

Explanation

6. What is the hydronium ion concentration of a 0.200 M solution of 3,6-dinitrophenol (Ka = 7.1×10–6)?

A. 8.4×10–4 M
B. 1.2×10–3 M
C. 2.7×10–3 M
D. 6.0×10–3 M
E. 8.4×10–3 M

Explanation

7. The solubility of PbBr2 in pure water at 20 °C is 0.884 g/100 mL. What is Ksp for lead bromide at this temperature?

A. 2.8
B. 6.9×10–3
C. 2.4×10–3
D. 5.6×10–5
E. 2.8×10–5

Explanation

8. A 5.00 g sample of a metal is heated to 100.00 °C and placed in a perfectly insulated container holding 20.00 g of water at 25.00 °C. After a few minutes the tmperature of the metal and the water are 26.69 °C. What is the specific heat (in units of J/g·K) of the metal? (specific heat of water = 4.184 J/g·K)

A. 0.0922
B. 0.0964
C. 0.386
D. 1.93
E. 141

Explanation

9. Eight people standing on a scale have a total weight of 1118 pounds. To the correct number of significant figures, what is the average weight of the people on the scale?

A. 100
B. 140
C. 139.8
D. 139.75
E. 139.7

Explanation

10. In the following, which is the oxidizing agent?

3 Fe2+ + CrO42– + 8 H+ → 3 Fe3+ + Cr3+ + 4 H2O

A. Fe2+
B. CrO42–
C. H+
D. Cr3+
E. H2O

Explanation

11. The principle type of bonding in NaCl is

A. non-polar
B. polar covalent
C. van der Waals forces
D. ionic
E. hydrogen bonding

Explanation

12. The hybrid orbitals whose angles to one another are 180° are

A. s
B. sp
C. sp2
D. sp3
E. p

Explanation

13. Which of the following is not an electrolyte when dissolved in water?

A. sodium chloride
B. sugar
C. sulfuric acid
D. potassium hydroxide
E. bicarbonate of soda

Explanation

14. What is the oxidation number of I in KIO4?

A. 3
B. 4
C. 5
D. 6
E. 7

Explanation

15. According to Le Chatelier's Principle, which of the following would shift the equilibrium reaction shown below to the right?

2 F2(g) + Si(s) ⇔ SiF4(g)    ΔH = –1614 kJ/mole

A. increase the temperature
B. increase the volume
C. add SiF4
D. add Si
E. add F2

Explanation

16. What is the wavelength (in meters) of light that corresponds to an energy of 1.00×10–5 J?

A. 5.03×1029
B. 1.99×10–20
C. 6.63×10–29
D. 1.99×10–30
E. 1.36×10–68

Explanation

17. Which of the following would you expect to have the highest boiling point?

A. CH3-CH=CH2-CH2-OH
B. CH3-CH=CH-O-CH3
C. CH2=CH-O-CH2-CH3
D. O=CH-CH2-CH2-CH3
E. CH2=CH-CH2-CH3

Explanation

18. Combustion of 1.000 g of a pure material in oxygen produced 1.782 g of carbon dioxide and 0.729 g of water and nothing else. What is the ratio of carbon to oxygen in the original molecule?

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

Explanation

19. What is the correct equilibrium mass action expression for the following reaction?

Ca(HCO3)2(s) ⇔ CaO(s) + 2 CO2(g) + H2O(g)

A. [CaO][CO2][H2O]/[Ca(HCO3)2]
B. [Ca(HCO3)2]/[CaO][CO2][H2O]
C. [CaO][CO2]2[H2O]/[Ca(HCO3)2]
D. [Ca(HCO3)2]/CaO][CO2]2[H2O]
E. [CO2]2[H2O]

Explanation

20. A compound has a per cent composition of 40.81 % C, 6.17 % H, 43.40 % O, and 9.52 % N. What is the empirical formula of this compound?

A. C4H8O5N
B. C5H9O4N
C. C6H12O5N
D. C7H14O5N
E. C41H6O43N10

Explanation

21. When the following equation is balanced and the coefficient of Mo24O37 is 1, the coefficient of KMnO4 is

Mo24O37 + KMnO4 + H2SO4 → MoO3 + MnSO4 + K2SO4 + H2O

A. 11
B. 12
C. 13
D. 14
E. 15

Explanation

22. A chemical company sells 99.99% pure mercury at $32.80 for 50.00 g. The density of mercury is 13.546 g/mL. What is the price of mercury in dollars per mL?

A. $22,220/mL
B. $121.06/mL
C. $8.886/mL
D. $0.1125/mL
E. $0.004882/mL

Explanation

23. A sample of hydrated calcium pyrophosphate weighing 1.912 g is heated until all of the water is driven off. The residue, anhydrous calcium pyrophosphate (molar mass = 254.10 g/mol) weighs 1.412 g. The formula for hydrated calcium pyrophosphate is Ca2P2O7·XH2O, X is

A. 2
B. 3
C. 4
D. 5
E. 9

Explanation

24. A 0.250 M solution of K2Cr2O7 (molar mass = 294.21 g/mol) has a density of 1.050 g/mL. What is the molality of this solution?

A. 0.238 m
B. 0.250 m
C. 0.256 m
D. 0.263 m
E. 70.0 m

Explanation

25. The mass percent of lead in lead metavanadate, Pb(VO3)2, is

A. < 30.00 %
B. 30.00 % – 39.99 %
C. 40.00 % – 49.99 %
D. 50.00 % – 60.00 %
E. > 60 %

Explanation

26. The density of a gas at 91.45 °C and 608 torr is 1.90 g/mL. What is the molar mass of this gas?

A. 20.2
B. 37.4
C. 71.1
D. 83.8
E. 154

Explanation

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