6. Three cylinders labeled A, B, C, are all at the same temperature. The volumes of the containers are 2.0 L, 4.0 L, and 6.0 L, respectively. Cylinder A contains 0.679 grams of neon gas at a pressure of 120 mmHg, cylinder B contains 2.45 grams of nitrogen gas at a pressure of 210 mmHg, and cylinder C is completely empty at the start. If the contents of A and B were completely transferred to C (assuming ideal conditions), what would the pressure become in cylinder C?
(A)0.25 atm
(B)180 mmHg
(C)330 mmHg
(D)675 mmHg
(E)1980 mmHg
This is a fairly difficult question, but perhaps more importantly, the question is long and complicated looking. By the time the hasty student finishes reading it, he or she might have forgotten the beginning of the question and decided to simply add the pressures together and choose an incorrect answer, C. To avoid situations like this, take a moment to truly understand the question before answering it. Read the question and then vocalize to yourself what the question is asking and what the pertinent information they give you is. Then go ahead and answer the question or solve the problem before you even look at the answer choices. This will help ensure that you aren’t seduced by any of the incorrect answer choices listed. By the way, the correct answer to this question is B. General Hint 6: Know How to Guess ETS doesn't take off 1 /4 of a point for each wrong answer to punish you for guessing—they do it so you won't get a reward for guessing blindly. Suppose that without even glancing at any of the questions, you just randomly entered responses in the first 20 spaces on your answer sheet. Because you have a 20% chance of guessing correctly on any given question, odds are you would guess right for four questions and wrong for 16 questions. Your raw score for those 20 questions would then be
(41) - (16 1/4) = 0
As you can see, you'd be no better or worse off blindly guessing than if you'd left those 20 spaces blank. Now suppose that in each of the first 20 questions you are able to eliminate just one possible answer choice, so that you guess with a 25% chance of being right. Odds are, you’d get five questions right and 15 questions wrong, giving you a raw score of
(51) - (15 1/4) = 1.25
All of a sudden, you're over a point up. It isn't much, but every little bit helps. Here's a list of your priorities when you come to each question on this test.First priority:
Answer the question correctly.
Second priority:
If you don't know the answer, try to eliminate answer choices and then guess.
Third priority:
If you can't eliminate any answer choices, circle the question and move on to the next one. You might have time to come back to it when you've finished the other questions.
The lesson to be learned here is that blind guessing doesn't help, but educated guessing does. If you can eliminate even one of the five possible answer choices, you must guess. We'll discuss how to eliminate answer choices on certain special kinds of questions in Chemistry Hint 5. Guessing as Partial Credit Some students feel that guessing is similar to cheating—that guessing correctly means getting credit where none is due. But instead of looking at guessing as an attempt to gain undeserved points, you should see it as a form of partial credit. For example, suppose you're stumped on the question above that asks about total pressure after different gases are mixed into a new container. And suppose you're pretty sure that the answer isn't simply adding the pressures given, even though you know Dalton's law of partial pressures. You do know many gas laws but are a little unsure as to how to answer this question. You do know that the pressure will be less or at least close to the other two pressures because you have some knowledge of Boyle’s law. Don't you deserve something for that extra knowledge? Well, you do get something: when you look at this question, you can throw out answer choices C and E, which leaves you with a one-in-three chance of getting the question right if you guess. Your extra knowledge gives you better odds of getting this question right, exactly as extra knowledge should.英语作文
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