If you’re wondering, the answers to the above questions are 1 A, 2 E, and 3 D.
“EXCEPT” Questions
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All of the following are true about an  -particle EXCEPT |
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(A) |
It has an atomic mass of 4 |
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(B) |
It carries a positive charge |
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(C) |
It is identical to the nucleus of a helium atom |
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(D) |
It will always pass right through a thin sheet of gold foil |
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(E) |
It contains two neutrons | |
Questions of the “EXCEPT” variety contain a bunch of right answers and one wrong answer, and it’s generally possible to spot one or two right answers. Even if you can’t answer the question confidently, you might remember that alpha particles have a positive charge and that they are identical to the nucleus of a helium atom. Already, you’ve eliminated two possible answers, and can make a pretty good guess from there.
If you’re interested, the answer is D: Rutherford’s gold foil experiment showed that alpha particles would occasionally deflect off the gold foil at extreme angles, thus proving that atoms have nuclei.
“I, II, and III” Questions
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For which of the following is f > 0: |
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I. Concave mirror
II. Convex mirror
III. Converging lens
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(A) |
I only |
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(B) |
II only |
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(C) |
I and III only |
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(D) |
II and III only |
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(E) |
I, II, and III | |
In this style of multiple-choice question, the “I, II, and III” questions provide you with three possible answers, and the five answer choices list different combinations of those three. There’s an upside and a downside to questions like these. Suppose you know that a concave mirror has f > 0 and a convex mirror doesn’t, but you’re not sure about a converging lens. The downside is that you can’t get the right answer for sure. The upside is that you can eliminate B, D, and E, and have a 50% chance of guessing the right answer. As long as you’re not afraid to guess—and you should never be afraid to guess if you’ve eliminated an answer—these questions shouldn’t be daunting.
The value of f for a converging lens is positive, so the answer is C.
Physics Hint 6: Be Flexible
Knowing your physics formulas is a must, but they’re useless if you don’t know how to apply them. You will probably never be asked to calculate the force acting on an object given its mass and acceleration. Far more likely, you will be asked for the acceleration given its mass and the force acting on it. Knowing that F = ma is useless unless you can also sort out that a = F⁄m.
The ETS people don’t want to test your ability to memorize formulas; they want to test your understanding of formulas and your ability to use formulas. To this end, they will word questions in unfamiliar ways and expect you to manipulate familiar equations in order to get the right answer. Let’s look at an example.
