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Grade 12 Chemistry entrance exam, 2008 E.C. (2016)

Real questions from the Grade 12 university entrance exam in Chemistry, as students sat it in 2008 E.C. Every question comes with the correct answer and a worked explanation.

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  • Natural science stream

    Who sits it

  • 2008 E.C. (2016)

    Exam year

  • 68 questions with answers

    In this set

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Answer each question yourself before opening the answer. The explanations point to the exact place in the textbook, so you know which page to reread when you miss one.

Question 1

A drug decomposes by zero-order kinetics with a rate constant of 2 mgmL−1 month−12\,\mathrm{mgmL^{-1}}\ \mathrm{month^{-1}}. If the initial concentration is 100 mgmL−1100\,\mathrm{mgmL^{-1}}, how long will it take for the drug to decompose by 10%?

  1. A.2 months
  2. B.3 months
  3. C.5 months
  4. D.4 months
Show the answer and explanation

Answer: C 5 months

Why

For a zero-order reaction, the amount decomposed is given by x = k * t. A 10% decomposition of 100 mg/mL corresponds to 10 mg/mL, so t = (10 mg/mL) / (2 mg/(mL*month)) = 5 months.

Question 2

The value of Keq\mathrm{K_{eq}} for the following reaction is 0.25. SO2 (g)+NO2(g)⇌2SO3(g)+NO (g)\mathrm{SO_2\ (g) + NO_2(g) \rightleftharpoons 2SO_3(g) + NO\ (g)} What is the value of Keq at the same temperature for the reaction below? 2SO2 (g)+2NO2 (g)⇌2SO3 (g)+2NO (g)\mathrm{2SO_2\ (g) + 2NO_2\ (g) \rightleftharpoons 2SO_3\ (g) + 2NO\ (g)}

  1. A.0.25
  2. B.0.062
  3. C.0.50
  4. D.16
Show the answer and explanation

Answer: B 0.062

Why

Multiplying the coefficients of an equilibrium reaction by a factor of 2 squares the equilibrium constant, so Keq' = (0.25)^2 = 0.0625, which rounds to 0.062.

Question 3

Which of the following would react to form pentyl ethanoate?

  1. A.1- propanol and pentanoic acid
  2. B.Ethanol and pentanoic acid
  3. C.1- pentanol and ethanoic acid
  4. D.Ethanol and ethanoic acid
Show the answer and explanation

Answer: C 1- pentanol and ethanoic acid

Why

Pentyl ethanoate is an ester formed by the Fischer esterification of 1-pentanol (providing the pentyl group) and ethanoic acid (providing the ethanoate group).

Question 4

Which of the following is correct when 34495 is rounded to three significant figures?

  1. A.345
  2. B.34500
  3. C.344
  4. D.3840
Show the answer and explanation

Answer: B 34500

Why

Rounding 34495 to three significant figures requires looking at the fourth digit (9), which rounds the third digit (4) up to 5, resulting in 34500.

Question 5

What is the first step of the scientific method?

  1. A.Making observations
  2. B.Forming a hypothesis
  3. C.Performing an experiment
  4. D.Predicting the result of an experiment
Show the answer and explanation

Answer: A Making observations

Why

The scientific method traditionally begins with making observations about a phenomenon, which then leads to asking a question and formulating a hypothesis.

Question 7

What is the distance that a radio wave will travel in 0.250sec?

  1. A.1.2×1071.2 \times 10^{7}m
  2. B.12×10712 \times 10^{7}m
  3. C.7.5×1077.5 \times 10^{7}m
  4. D.5.6×1075.6 \times 10^{7}m
Show the answer and explanation

Answer: C 7.5×1077.5 \times 10^{7}m

Why

Radio waves travel at the speed of light (c = 3.0 x 10^8 m/s). The distance traveled in 0.250 s is (3.0 x 10^8 m/s) * 0.250 s = 7.5 x 10^7 m.

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Chemistry papers from other years

2018 E.C. (2026)2017 E.C. (2025)2016 E.C. (2024)2015 E.C. (2023)2014 E.C. (2022)2013 E.C. (2021)2012 E.C. (2020)2011 E.C. (2019)2010 E.C. (2018)2009 E.C. (2017)2007 E.C. (2015)2006 E.C. (2014)2005 E.C. (2013)

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Are these the real 2008 E.C. Chemistry entrance exam questions?

Yes. They come from the national university entrance exam in Chemistry that students sat in 2008 E.C. (2016). Our set holds 68 of its questions, each with its answer and an explanation that points back to the textbook.

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Can I download the Chemistry 2008 E.C. paper as a PDF?

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