Five-Choice Completion Questions
These are the multiple-choice questions we all know and love, and which are the lifeblood of any multiple-choice exam. You know the drill: they ask a question and give you five possible answer choices, and you pick the best one. This will be the third and final part of the exam.
Here are the directions you’ll see on the exam:
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Directions: Each of the questions or incomplete statements below is followed by five suggested answers or completions. For each question, select the one choice that is the best answer to the question and then fill in the corresponding oval on the answer sheet.
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| 24. |
Which of the following molecules does not match its geometric shape? |
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(A) |
BF3 |
trigonal planar |
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(B) |
CHCl3 |
tetrahedral |
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(C) |
H2O |
V shape (bent) |
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(D) |
CO2 |
linear |
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(E) |
PCl3 |
trigonal planar | |
The answer is E—the shape of this compound is irregular tetrahedron (also known as trigonal pyramid). You’ll learn rules for predicting molecular structures in chapter 4. Now, the above question is a straightforward multiple choice, but there’s another type of five-choice completion question on the test, and it looks like the question below:
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| 25. |
Which of the following statements correctly describe the necessary for finding the concentration of an unknown monoprotic acid by titration with KOH? |
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I. The concentration of the base
II. The total starting volume of acid
III. The volume of the base used to reach the equivalence point
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(A) |
I only |
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(B) |
II only |
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(C) |
I and II only |
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(D) |
I and III only |
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(E) |
I, II, and III | |
Let’s analyze it. To find the concentration of the unknown acid, you’ll need to know the molarity of the base used in the titration or, put in simpler language, the moles of base per liter of solution. So, statement I is necessary. We’ll also need the in statements II and III, as you’ll learn in “Laboratory.” The correct answer is E.
While knowing your chemistry inside and out is the best way to ensure that you’ll do well on this test, it will also help you on test day if you’ve developed a strategy that enables you to answer all the questions that test you on chemistry you feel confident about and to guess intelligently on the questions on areas in which you feel less confident. We will talk about some strategies for how to deal with these harder questions in the next chapter
