CBT AAMC3 Megatopic, advice for CBT AAMC4?

[pfaction]

11/10/9.
I made reading mistakes, yes. So many. But I don't understand the following:

PS:
#4: Each solution contains the same moles of ions: 0.300. However, SO4 and CO3 are 2- whereas I is -1. PB is 2+. So I thought I would have precipitated first solely on virtue of PBI2. How are you supposed to assume that PBCO3 is less soluble than PBI, which is less soluble than PBSO4?

#11 - how are we supposed to know that? I combed over the passage and found no information on it.

#15 - I got it right, but I just did a right triangle. 3, 4, therefore magnitude must be 5. So F, no matter what the arc tan is (I don't even know what Arctan is) has to be 5...

#17 - got it right, but I don't understand why. The BP is 80, what would it matter if temp is 100 or 90? the amount of collissions heating it up?

#33 - I got it right, but the question says "molecular weight alone". I would have chosen D because the MW's are so similar...

#41 - I have a weakness here I need to go over but I still don't understand it.

#51 - why isn't this B? I know it gets promoted, but I thought the rest of the energy would be lost trying to get it up to the next level and failing.

Verbal: I got 32, so close to an 11. Won't bother going over it, what I got wrong I got wrong. But, for those who took AAMC4 and up, is this the easiest Verbal? Should I not feel comforted? I also hear the actual MCAT Passages are longer, I'm "struggling" at 8 mins/passage, should I be worried?

Bio:
I didnt understand the first passage at all, yet got all the questions right. After re-reading I think I need to review genetics completely. I understood the second one, but took a lot of POE and guesswork.

#107 - I got it wrong because it said HETEROZYGOUS, not homozygous - reading error. But if it were heterozygous, would the answer be 0?

#111 - ebulliaton. Introducing small air bubbles, how does this work? I got it right solely due to MedPR's topic. TPR makes no mention of this.

#112 and #114 - I got it wrong. I don't see why it is true though.

#115 - I assumed this was X-linked recessive. So, I made it XaY + XAXA OR XAXa. The passage states that no females ever get it though, so I should probably have realized it's always dominant....but there is a chance it could be XAXa.

So when I did a cross, I found that males had a 50% chance (Xa from mother or XA from mother) and females had a 50% chance (Xa from dad, either XA or Xa from mother)...but the answer was none and none?

#121 and #122 - I was never taught this. WTF?

#123 - since cyclopropane is the most unstable, shouldn't it take the least amount of energy to break it up?

Passage V: Holy **** I did NOT understand this at all. I was on it for a good 15 minutes after skipping it initially.

#127 and 128 - what?! I didn't understand this at all. For 127, I thought ADH would kick in. #128 I guessed on and got it right but I still don't understand it.

#134 - Mehhh I can kind of understand it, but not fully.

#146 - do not understand at all.


So I'm taking AAMC 4 on Tuesday or Wednesday. Any words of advice for me?

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[MedPR]

Is this CBT or the paper version? Also you're probably better off making individual threads or at least threads for each topic. I don't think many people are going to pull up their copy of the test and look up what you are asking about.

I do happen to remember #4 and the answer to that is recognizing the order that the reactions were carried out in the experiment. You wouldn't precipitate out the least soluble first, you would do it last.

 

[pfaction]

It's the CBT, I thought they were both the same. Sorry, I'll update the topic.

 

[MedPR]

It's the CBT, I thought they were both the same. Sorry, I'll update the topic.

There are pdf copies of the old tests floating around the internet (as someone in the MCAT discussion thread pointed out).

You can leave your thread like this if you want, but I think you will get more help if you typed out each question or took a screenshot. Make sure you put AAMC 3 in your thread titles

 

[pfaction]

I don't want to spam a ton of topic, you know what I mean? Plus I'm taking another exam in 2 days so it'd take forever as it is. But I guess I need a concept review. I still don't understand #4 though. Any way you can explain it? They were separated reactions.

 

[MedPR]

I don't want to spam a ton of topic, you know what I mean? Plus I'm taking another exam in 2 days so it'd take forever as it is. But I guess I need a concept review. I still don't understand #4 though. Any way you can explain it? They were separated reactions.

First PbSO4 is formed, then PbI2, then PbCO3. If PbSO4 was less soluble than PbI2, how would you get PbI2 to precipitate from PbSO4? You wouldn't, because the PbSO4 would never dissolve to allow Pb2+ to bond to I-. PbSO4 has to be more soluble than PbI2. Same is true for PbI2 and PbCO3. PbCO3 must be the least soluble if it is going to precipitate out.

 

[misseskwee]

Here's a couple,
#121 - taxonomy- Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species.
(Decreasing order) So the lower, the closer related. I use the mnemonic D King Plays Chess On Fine Green Spaces

#122 - Yea i learned it in Psych classes, I guess it's just something not something you find in mcat books, so maybe a little unfair.

#123 - cyclohexane is most stable so it requires the least energy in combustion reactions.

#134 - they mentioned osteoporosis was due to decreased estrogen levels in post-menopausal women. So if a man was given estrogen treatment, no reason for him to get osteoporosis.

Idk if i helped but i hope i did. I'd try to answer more but i'm watching "what's your number" to relax myself before tomorrow's aamc5 lol

 

[pfaction]

Still not seeing it MedPR, will review tomorrow.

Yeah it helped. I didn't know and wasn't taught taxonomy, so I'll keep it in mind.
123 I understand but isn't it asking for least, so if something is unstable it should take more to break it up, right?
134, okay, I kind of see it, I thought that it would be decreased due to estrogen therapy, I guess that was just for women though

 

[misseskwee]

123-Yea they asked for least energy (heat of combustion) so that'll correspond to the one that's most stable.

 

[pfaction]

Oops I must have mistyped. I meant to say, if something is UNSTABLE, shouldn't it take LESS energy? To break up cyclohexane, I thought, since it's stable, would take more heat. I don't understand this either. ****.

 

[MedPR]

Still not seeing it MedPR, will review tomorrow.

Yeah it helped. I didn't know and wasn't taught taxonomy, so I'll keep it in mind.
123 I understand but isn't it asking for least, so if something is unstable it should take more to break it up, right?
134, okay, I kind of see it, I thought that it would be decreased due to estrogen therapy, I guess that was just for women though

122: You can kind of guess at this based on the non-science definitions of the words.

123: Cyclohexane is the most stable. So when you combust it, you will be consuming a lot of energy and thus will not be releasing very much. When you combust cyclopropane, which is already very unstable and at a very high energy level, you don't need to input very much energy and thus will get a more exothermic reaction.

Alternatively you can think of it as a mountain/valley type of problem. Cyclohexane has very low energy since it is very stable. You need to climb a very high mountain to get it to combust.
Cyclopropane is very unstable, so it is at a very high energy level. You could probably poke cyclopropane with a stick and it would fall all the way down into an energy valley.

134: Yea, it's just comprehension of the passage.

 

[pfaction]

So this is another question where I don't understand both the content, and the actual question. I thought they were asking for the amount of heat needed to break the cyclo group up. I was wrong. They were asking for the amount of energy released per methylene group. If they asked for the most energy released I think it would be cyclopropane.

I feel like a ****ing *****. I can't understand most of these questions. So your explanation is that since it takes more energy to blow cyclohexane apart, the deltaH would be less than cyclopropane or butane because those would be much more prone to blow up, requiring less input and thus deltaH would be much more negative.

 

[MedPR]

So this is another question where I don't understand both the content, and the actual question. I thought they were asking for the amount of heat needed to break the cyclo group up. I was wrong. They were asking for the amount of energy released per methylene group. If they asked for the most energy released I think it would be cyclopropane.

I feel like a ****ing *****. I can't understand most of these questions. So your explanation is that since it takes more energy to blow cyclohexane apart, the deltaH would be less than cyclopropane or butane because those would be much more prone to blow up, requiring less input and thus deltaH would be much more negative.

Yup. Exothermic = weak bonds broken, strong bonds formed. If you start with strong bonds you won't have a very exothermic result.

 

[pfaction]

****ing reading and reading comprehension errors. This test on Tuesday is NOT going to go well for me.