2008 Avogadro Exam

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6. Now answer the exam questions. Questions are not in order of difficulty. Indicate your choice on the STUDENT RESPONSE sheet by marking one letter beside the question number.
   • Mark only one answer for each question.
   • Questions are all of the same value.
   • There is a penalty (1/4 off) for each incorrect answer, but no penalty if you do not answer.
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   Be careful that any erasures are complete—make the sheet white again.

1. Which of the following elements is not a metal?

1. Se
2. Sn
3. Sr
4. Sc
5. Cs

2. A colourless, odourless gas is thought to be oxygen.

Which of the following experimental results would support this conclusion?

1. Burning the gas in air produces only water.
2. The gas extinguishes a flame.
3. The gas turns a Ca(OH)₂ solution milky.
4. A glowing piece of wood bursts into flames in the gas.
5. The gas tarnishes silver.

3. Which of the following particles is the most massive?

1. α-particle
2. β-particle
3. electron
4. proton
5. neutron

4. What volume of 5.0 mol L⁻¹ H₂SO₄(aq) must be diluted with water to make 1.00 L of 0.45 mol L⁻¹ H₂SO₄(aq)?

1. 0.090 L
2. 0.44 L
3. 0.090 mL
4. 0.045 L
5. 2.22 mL

5. How many neutrons are there in the nucleus of ¹³¹I?

1. 44
2. 53
3. 78
4. 131
5. 184

6. Which group of elements contains no metals or metalloids?

1. group 13
2. group 14
3. group 15
4. group 16
5. group 17

7. Which of these chloride salts is least likely to exist?

1. NaCl
2. CuCl
3. CaCl₂
4. FeCl₃
5. MgCl

8. When a sample of atomic hydrogen gas is heated, it emits violet, blue, green and red light.

Which of the following statements best explains this observation?

1. The energy of the electron in a hydrogen atom is restricted to certain values.
2. The energy of the electron in a hydrogen atom is not restricted in any way.
3. The electron in a hydrogen atom is restricted to one of only four possible circular orbits.
4. The distance between the electron and the nucleus in a hydrogen atom is restricted to certain values.
5. none of the above

9. Which of the following is not a mixture?

1. seawater
2. table sugar
3. brass
4. cement
5. smoke

10. Radioactive ¹³¹I is used to treat thyroid cancer.

An incomplete chemical equation for the radioactive decay of ¹³¹I is given below.

¹³¹I → ? + ⁰_-1e

What is the missing product in the equation above?

1. ¹³⁰I
2. ¹²⁹I
3. ¹³¹Xe
4. ¹³¹Te
5. ¹³¹I⁺

11. Which of the following has the highest concentration in air at STP?

1. He
2. H₂O
3. CO₂
4. N₂
5. O₂

12. The average mass of a solid copper penny is 2.63 g.

What is the mass of one mole of pennies?

1. 1.58×10²⁴ g
2. 6.02×10²³ g
3. 6.36×10²³ g
4. 63.6 g
5. 1.58×10²³ g

13. What is the sum of the coefficients when the following equation is balanced using the smallest whole number coefficients?

P + Cl₂ → PCl₃

1. 12
2. 11
3. 6
4. 5
5. 3

14. How many litres of gaseous methane (CH₄) must be burned in oxygen to produce enough H₂O and CO₂ to fill a 3.0-L balloon?

Assume that H₂O and CO₂ are the only combustion products and that the temperature and pressure remain constant.

1. 1.0 L
2. 1.5 L
3. 2.0 L
4. 2.5 L
5. 3.0 L

15. A compound that contains only Fe and O is 69.9% Fe by mass.

What is the empirical formula of this compound?

1. FeO
2. FeO₂
3. Fe₂O₃
4. Fe₂O
5. Fe₃O₄

16. If 17.0 grams of sodium chloride are dissolved in water to make 0.5 L of solution, then what is the final concentration of the solution?

Give your answer with the correct number of significant figures.

1. 0.6 mol L^-1
2. 0.58 mol L^-1
3. 0.581 mol L^-1
4. 0.3 mol L^-1
5. 0.291 mol L^-1

17. What is the effect of adding a catalyst to a reaction mixture?

1. It increases the equilibrium concentrations of the products.
2. It decreases the enthalpy change of the reaction.
3. It reduces the activation energy of the reaction.
4. It increases the value of the equilibrium constant for the reaction.
5. It increases the time it takes for the reaction to reach equilibrium.

18. How many valence electrons are there in one Al³⁺ ion?

1. 2
2. 4
3. 6
4. 8
5. 10

19. What volume of He(g) contains the same number of moles of gas as 1.00 L of N₂(g) at the same temperature and pressure?

1. 7.00 L
2. 1.00 L
3. 0.143 L
4. 35.7 mL
5. 4.00 L

20. What is the HNH bond angle in an ammonia (NH₃) molecule?

Choose the closest value.

1. 90°
2. 45°
3. 120°
4. 109°
5. 180°

21. Which of the following types of radiation has the lowest energy per photon?

1. radio waves
2. ultraviolet radiation
3. infrared radiation
4. x-rays
5. purple laser light

22. An incomplete Lewis structure (i.e. electron dot structure) for the O₃ molecule is given below.

O—O—O

How many lone pairs of electrons are there in the completed structure?

1. two
2. four
3. five
4. six
5. eight

23. Which of the following is not a common oxide of nitrogen?

1. NO
2. NO₂
3. N₂O₄
4. N₂O
5. NO₃

24. In an experiment, 0.12 L of 0.10 mol L^-1 H₂SO₄(aq) and 0.20 L of 0.10 mol L^-1 NaOH(aq) are combined.

Which of the following statements is true?

1. The pH of the resulting solution is less than 7.
2. The pH of the resulting solution is greater than 7.
3. The pH of the resulting solution is close to 7.
4. The pH of the resulting solution is exactly 7.
5. None of the statements above are true.

25. Solid aluminum dissolves in hydrochloric acid solution according to the following chemical equation.

2 Al(s) + 6 HCl(aq) → 2 AlCl₃(aq) + 3 H₂(g)

How many moles of H₂ are produced if 17.5 moles of Al are added to a solution containing 24.8 moles of HCl?

1. 26.3 mol
2. 12.4 mol
3. 7.30 mol
4. 17.5 mol
5. 24.8 mol

26. Which of the following choices does not involve a chemical change?

1. evaporation and neutralization
2. neutralization and sublimation
3. oxidation and sublimation
4. evaporation and sublimation
5. neutralization and oxidation

27. Which of the following atoms or ions has the electron configuration 1s²2s²2p⁶3s¹ in its ground electronic state?

1. Na
2. Mg⁺
3. K
4. Ca⁺
5. Al³⁺

28. Which of the following is a brittle solid and an electrical insulator at room temperature, but an excellent electrical conductor in its liquid form?

1. sulphur
2. sodium chloride
3. aluminum
4. mercury
5. carbon

29. Which of the following salts produces a basic solution when it is dissolved in water?

1. KCl
2. NH₄Cl
3. K₂CO₃
4. NaNO₃
5. CuBr₂

30. Which of the following describes the process that produces Fe(s) from Fe₂O₃(s)?

1. combustion
2. precipitation
3. hydrolysis
4. reduction
5. oxidation

31. Which one of the following solutions will be the worst electrical conductor at 25°C?

1. 0.10 mol L^-1 Na₂SO₄(aq)
2. 0.10 mol L^-1 NaCl(aq)
3. 0.10 mol L^-1 CaSO₄(aq)
4. 0.10 mol L^-1 CH₃OH(aq)
5. 0.10 mol L^-1 CsCl(aq)

32. Which of the following atoms is not present in large numbers in biological molecules?

1. C
2. F
3. O
4. N
5. H

33. In which of these compounds is the oxidation state of Cl the highest?

1. HClO₂
2. ClO₂
3. Cl₂O₅
4. Cl₂O
5. HClO₄

34. Which of the gases most closely resembles an ideal gas at standard temperature and pressure?

1. CO₂
2. NH₃
3. HI
4. H₂
5. H₂O

35. Which of the following have ground state electron configurations of the type ns²np²?

1. group 2 atoms
2. group 4 atoms
3. group 6 atoms
4. group 14 atoms
5. group 16 atoms

36. Which of the species in the reaction below are Brønsted-Lowry acids?

HSO₄^- + HCO₃^- ⇌ SO₄^2- + H₂CO₃

1. HSO₄^- and HCO₃^-
2. HSO₄^- and H₂CO₃
3. HCO₃^- and SO₄^2-
4. SO₄^2- and H₂CO₃
5. HSO₄^- and SO₄^2-

37. Which of the following is not an alkane?

1. C₂H₄
2. C₃H₈
3. C₄H₁₀
4. C₅H₁₂
5. C₆H₁₄

38. What happens when a solution of lithium chloride (LiCl) and a solution of ammonium nitrate (NH₄NO₃) are mixed?

1. A precipitate forms.
2. A new salt is formed.
3. A gas is evolved.
4. A metal is formed.
5. No reaction occurs.

39. An average person expends approximately 100 kJ to walk 1 km.

How far will the average car travel by the time it expends the same amount of energy (i.e. 100 kJ) as a person who walked 1 km?

Use the data given below to determine the answer.

Choose the closest answer.

• Fuel consumption of an average car, 8 km L⁻¹

• Heat of combustion of gasoline, 50 kJ g⁻¹

• Density of gasoline, 0.7 g mL⁻¹

1. 2 km
2. 0.2 km
3. 0.02 km
4. 20 km
5. 200 km

40. How many structural isomers are there for C₆H₁₂?

1. less than three
2. three
3. four
4. five
5. more than five

AVOGADRO EXAM 2009 DATA SHEET

DETACH CAREFULLY

Additional interactive periodic tables

• Royal Society of Chemistry
• Fisher Scientific
• National institutes of Health

Constants

N_A = 6.022 x 10²³ mol^-1
R = 0.08206 atm L K^-1 mol^-1 = 8.3145 kPa L K^-1 mol^-1 = 8.3145 J K^-1 mol^-1

K_w = 1.0 \times 10^{-14} (at 298 K)
F = 96 485 C mol^-1

Conversion factors

1 atm = 101.325 kPa = 760 torr = 760 mm Hg
0^oC = 273.15 K

Equations

PV = nRT
k t_1/2 = 0.693
pH = pK_a + log ([base]/[acid])

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