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it's a discrete so I'm sure it's pretty easy and there must be something that I'm missing, but low sexual dimorphism means that sexes look the same right?
confused with this question NS4 P/S #47
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Hi @br2pi5 -
Yes, that's correct about sexual dimorphism. The idea for this question is to recognize that high sexual dimorphism usually reflects intense mate competition and vice-versa, so a low sexual dimorphism situation would predict mating dynamics like those presented in choice A. Without more information about your reasoning process, it's hard to give a more detailed targeted explanation, but re: choice D, one thing to keep in mind is that sexual dimorphism refers primarily to physical differences between the sexes, not behavioral patterns like nest construction.
Hope this helps clarify the question!
Yes, that's correct about sexual dimorphism. The idea for this question is to recognize that high sexual dimorphism usually reflects intense mate competition and vice-versa, so a low sexual dimorphism situation would predict mating dynamics like those presented in choice A. Without more information about your reasoning process, it's hard to give a more detailed targeted explanation, but re: choice D, one thing to keep in mind is that sexual dimorphism refers primarily to physical differences between the sexes, not behavioral patterns like nest construction.
Hope this helps clarify the question!
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@NextStepTutor_1 hello! I wanted to check the way I went about answering this question and see if my reasoning is correct? the question tells us that NO2(OH) produced an acidic solution (creating H+ ions) therefore I immediately thought acid. For the Ni(OH)2 it said it only dissolved in an acidic solution, so I thought Le Chatelier's Principle, in that if there are already lots of H+ ions in solution it wouldn't make more H+ ions if it were an acid thus I ruled out that option and thought base? I got the correct answer but just want to see if I got lucky with my reasoning or if it made sense, thank you as always!! 
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Hi @br2pi5 -
For that first question from the AAMC sample test (C/P 12), you're on the right track about NO2(OH). Additionally, the passage tells us that this must be an acid, because the passage tells you that compounds where N is a nonmetal are acidic. For Ni(OH)2, the best indicator is that it dissolves in acidic solution. Le Chatelier's is relevant here, but I think in a slightly different way than you described -- instead, the way I'd suggest thinking about it is that for Ni(OH)2 to dissolve, OH- ions must go into solution. In an acidic environment, we'd expect those ions to react with H+ in solution to form H2O in classic acid-base neutralization chemistry. This would drive the dissolution of Ni(OH)2 forward through Le Chatelier's principle.
For that second question (AAMC sample C/P 46), that's a legitimately tough question and I think that each student has to make a decision about approaching questions like that based on their comfort level w/ the subject matter & timing situation - you don't want to waste 2+ minutes on this if that's going to keep you from getting doable questions right later on in the test. If you have a good sense of what the density of humans is and how that corresponds to apparent weight in the water, then sure, working backwards through estimation is viable. We know that humans have a density of close to 1 (the details depend on body composition, etc.) -- let's say the density of humans is 1.05, which means that a 100-pound human will have an apparent weight in the water (W_w) of 5 pounds. We can then plug those values in to the answer choices and see which result in a density slightly greater than 1, per our assumption: A gives us 100/(100-5) = 100/95, which is slightly >1, corresponding to our initial assumption. B gives us (100-5)/100, which is close to but slightly less than 1, unlike our assumption. C gives (100-5)/5, which is close to 20 and completely ridiculous. D gives us 5/(100-5), which is a tiny number that we can eliminate. So yes, this gives us the right answer, but it relies on some key background info.
Another useful way of solving this question is to note that the logic of the question tells us that we're looking for something proportional to the density of the human body, so we need to find an expression that could be written as [something]*rho(human). The weight of a human in air is going to be W_air = m_human*g = rho(human)*V_human*g, so an expression with W_air and nothing else in the numerator will be our best bet.
If you Google around for Q46, you'll find other explanations as well, including more thorough explanations of the underlying physics -- but I'm all about informed shortcuts, and answering Q's with the least reasonable amount of effort possible, so thought I'd share those approaches.
For that first question from the AAMC sample test (C/P 12), you're on the right track about NO2(OH). Additionally, the passage tells us that this must be an acid, because the passage tells you that compounds where N is a nonmetal are acidic. For Ni(OH)2, the best indicator is that it dissolves in acidic solution. Le Chatelier's is relevant here, but I think in a slightly different way than you described -- instead, the way I'd suggest thinking about it is that for Ni(OH)2 to dissolve, OH- ions must go into solution. In an acidic environment, we'd expect those ions to react with H+ in solution to form H2O in classic acid-base neutralization chemistry. This would drive the dissolution of Ni(OH)2 forward through Le Chatelier's principle.
For that second question (AAMC sample C/P 46), that's a legitimately tough question and I think that each student has to make a decision about approaching questions like that based on their comfort level w/ the subject matter & timing situation - you don't want to waste 2+ minutes on this if that's going to keep you from getting doable questions right later on in the test. If you have a good sense of what the density of humans is and how that corresponds to apparent weight in the water, then sure, working backwards through estimation is viable. We know that humans have a density of close to 1 (the details depend on body composition, etc.) -- let's say the density of humans is 1.05, which means that a 100-pound human will have an apparent weight in the water (W_w) of 5 pounds. We can then plug those values in to the answer choices and see which result in a density slightly greater than 1, per our assumption: A gives us 100/(100-5) = 100/95, which is slightly >1, corresponding to our initial assumption. B gives us (100-5)/100, which is close to but slightly less than 1, unlike our assumption. C gives (100-5)/5, which is close to 20 and completely ridiculous. D gives us 5/(100-5), which is a tiny number that we can eliminate. So yes, this gives us the right answer, but it relies on some key background info.
Another useful way of solving this question is to note that the logic of the question tells us that we're looking for something proportional to the density of the human body, so we need to find an expression that could be written as [something]*rho(human). The weight of a human in air is going to be W_air = m_human*g = rho(human)*V_human*g, so an expression with W_air and nothing else in the numerator will be our best bet.
If you Google around for Q46, you'll find other explanations as well, including more thorough explanations of the underlying physics -- but I'm all about informed shortcuts, and answering Q's with the least reasonable amount of effort possible, so thought I'd share those approaches
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