AAMC CBT10 only OFFICIAL Q&A

[Vihsadas]

This is the official Q&A thread for AAMC CBT10.

Please post ONLY questions pertaining to AAMC CBT10.
Out of respect for people who may not have completed the other exams, do not post questions or material from any other AAMC exam.

Please see this thread for the rules of order before you post.

Good luck on your MCAT!

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[Thisisthelife]

can anyone explain #112 about the hantavirus being complementary to the lung gene? Are they implying here that the DNA from the virus was incorporated into the lung genome via a lysegenic cycle? I'm a bit confused

Here they are testing to see if you understand how nucleic acid base pair. The only knowledge you need to answer this question is that nucleic acids base pair when they are complementary. By complementary they mean is the 5' end from one strand is G then the 3' end from the opposite strand must be C in order for them to be able to pair.

 

[bmoredoc]

Here they are testing to see if you understand how nucleic acid base pair. The only knowledge you need to answer this question is that nucleic acids base pair when they are complementary. By complementary they mean is the 5' end from one strand is G then the 3' end from the opposite strand must be C in order for them to be able to pair.

Hey thanks for the response. I understand complementary nucleic acids base pair. I just don't understand what it's base pairing to?

 

[RC4L]

Actually, if this option was "a cat to mice" it would probably have been the best option. I made the mistake of switching the answers in my head. If you read the question carefully, you'll notice that the first part of the analogy corresponds to the king and the second to the scientists NOT the other way around.

The relationship being questioned is one in which the king/dog is giving reluctant support to the founders of the royal societ/fleas. It is not life-threatening but it is irritating. If the king were the cat and the founders of the royal society were mice, that would constitute a reversal of their roles and the king we would have the complete advantage which would be false.

 

[pm1]

Which of the following reacts most violently in cold water?

K
Mg
Fe
Zn

I did think about the whole thing of periodic trends and K wanting to give electrons away more than anyone.

However, I did some over thinking. I remembered that KOH is a strong base and strong bases completely dissociate in water. Thus, KOH would not form, hence it couldn't be K. How is that thinking wrong/or not related to this?

Thank you!

 

[RC4L]

Which of the following reacts most violently in cold water?

K
Mg
Fe
Zn

I did think about the whole thing of periodic trends and K wanting to give electrons away more than anyone.

However, I did some over thinking. I remembered that KOH is a strong base and strong bases completely dissociate in water. Thus, KOH would not form, hence it couldn't be K. How is that thinking wrong/or not related to this?

Thank you!

I just remembered seeing in prep books that group 1 metals were the most reactive/dissolved easiest in water followed by group 2. It threw me off when they said react violently though.

 

[Yorick]

Which of the following reacts most violently in cold water?

K
Mg
Fe
Zn

I did think about the whole thing of periodic trends and K wanting to give electrons away more than anyone.

However, I did some over thinking. I remembered that KOH is a strong base and strong bases completely dissociate in water. Thus, KOH would not form, hence it couldn't be K. How is that thinking wrong/or not related to this?

Thank you!

Alkali (group 1) metals are the most reactive because they have 1 valence electron, which is very easy to lose.

 

[FeinMS]

That vole question was a bull. I just guessed mouse because the passage said the passage occured in rural area.

Anyone knows if anaerobic bacteria uses ATP synthase to produce ATP? I was debating between that and chemical composition of ribosome and chose the latter thinking there are lots of anaerobic bacteria and they, I thought, don't use oxidative phosphorylation to produce ATP..

 

[Bea5T]

That vole question was a bull. I just guessed mouse because the passage said the passage occured in rural area.

Anyone knows if anaerobic bacteria uses ATP synthase to produce ATP? I was debating between that and chemical composition of ribosome and chose the latter thinking there are lots of anaerobic bacteria and they, I thought, don't use oxidative phosphorylation to produce ATP..

What was the question stem?

 

[FeinMS]

Most bacterial cells and human cells are alike in their:
A: ATP production via ATP synthase
B: chemical composition of ribosome
C: presence of cell wall
D: something else that I could eliminate on the spot.

My reasoning for choosing B was that although the sizes of prokaryotic and eukaryotic ribosomes are diff, they're still made of rRNA and protein (same chemical composition.) Also I knew that some bacterias are anaerobic, so I thought they don't use ATP synthase. It turns out that anaerobic bacteria does use ATP synthase and ETC except that they don't use O2 as the final electron acceptor.

 

[gettheleadout]

Most bacterial cells and human cells are alike in their:
A: ATP production via ATP synthase
B: chemical composition of ribosome
C: presence of cell wall
D: something else that I could eliminate on the spot.

My reasoning for choosing B was that although the sizes of prokaryotic and eukaryotic ribosomes are diff, they're still made of rRNA and protein (same chemical composition.) Also I knew that some bacterias are anaerobic, so I thought they don't use ATP synthase. It turns out that anaerobic bacteria does use ATP synthase and ETC except that they don't use O2 as the final electron acceptor.

"Chemical composition" is vague, but they could mean mass percent ratios of atoms, in which case ribosomes of different sedimentation coefficients are likely different. I knew that bacteria use the p-type H+ ATPase, so knew A was correct and that B was less than ideal.

 

[keepcalm2]

BS #99) 1-Propanol and 1,2-ethanediol can be separated by which of the following techniques?

A) Extraction with ethanol
B) Extraction with water
C) Recrystallization
D) Fractional distillation

1- Propanol BP = 97C
1,2-ethanediol BP = 197C

why is the answer fractional distillation? i thought that can only be used in boiling point differences of 30C or less? that's what the berkeley review said

 

[FeinMS]

BS #99) 1-Propanol and 1,2-ethanediol can be separated by which of the following techniques?

A) Extraction with ethanol
B) Extraction with water
C) Recrystallization
D) Fractional distillation

1- Propanol BP = 97C
1,2-ethanediol BP = 197C

why is the answer fractional distillation? i thought that can only be used in boiling point differences of 30C or less? that's what the berkeley review said

I understand your concern, but nothing else is possible. A,B is basically the same and both 1-propanol and 1,2-ethanediol dissolves in ethanol and water, so useless. C is used for solids.

 

[gettheleadout]

BS #99) 1-Propanol and 1,2-ethanediol can be separated by which of the following techniques?

A) Extraction with ethanol
B) Extraction with water
C) Recrystallization
D) Fractional distillation

1- Propanol BP = 97C
1,2-ethanediol BP = 197C

why is the answer fractional distillation? i thought that can only be used in boiling point differences of 30C or less? that's what the berkeley review said

Fractional distillation should only be used when components have very similar boiling points, but this is for efficiency reasons. You can use fractional distillation anytime you can use simple distillation, it just may not be the best choice for yield, time, etc.

 

[keepcalm2]

thanks guys! that's annoying, wish they just had simple distillation as an answer instead of trying to trick us -.-

 

[pinklefluff]

Can someone explain both 43 and 46?

As far as 43 goes, I assumed that you would have equal forces pulling on the ionization trail, preventing the ions from accelerating to in either direction, i.e. no anode signal would be detected.


As far as 46 goes, are we supposed to make this inference based on the vocabulary used and POE?

For 46 I just thought of it the more anodes you have in a given space, the more detailed information of the location you will get since the passage say that the anodes provide three-dimensional information.

I am also very confused about 43... did someone understand this?

 

[sweetx56]

For 46 I just thought of it the more anodes you have in a given space, the more detailed information of the location you will get since the passage say that the anodes provide three-dimensional information.

I am also very confused about 43... did someone understand this?

For 43, it seemed confusing at first, but then I just visualized the multiwire proportional chamber to being lots of singlewire proportional chambers compacted together. In the passage for the singlewire chamber it says that each anode wire has its own amplifier that sends a signal to the computer. In the singlewire chamber a charged particle creates a cascading effect ionizing other molecules down the chamber so I imagined this would occur with multiple signals in the multiwire chamber as long as the ionization trail is close enough to be picked up by the anode and have information amplified and brought back to the computer.

Likewise, A and B are inferences that have nothing to do with what was stated in the passae, and C is completely wrong as that would cause the oppositve effect so it must be D.

 

[sweetx56]

"Chemical composition" is vague, but they could mean mass percent ratios of atoms, in which case ribosomes of different sedimentation coefficients are likely different. I knew that bacteria use the p-type H+ ATPase, so knew A was correct and that B was less than ideal.

The answer is 100% A because with knowing the endosymbiotic theory, eukaryotic mitochondria are expected to have derived from an aerobic prokaryote and so have nearly the exact same structures and mechanisms in it when it comes to the DNA, ETC and ATPase inside the mitochondria.

 

[danny89]

Can someone explain to me for #1 why the copper oxidation state in the penny is 0? Isn't it +2?

 

[sazerac]

Can someone explain to me for #1 why the copper oxidation state in the penny is 0? Isn't it +2?

The oxidation state of any element in its natural non-ionized form is zero. Copper in a penny is just elemental copper metal.

 

[danny89]

For #47 in PS: What particle would produce the largest anode signal when transversing a proportional chamber with an initial speed of 99% that of light?
Why is the answer an alpha (helium) particle? The answer says it's due to it's +2e charge; however, doesn't it have 2 protons and 2 neutrons, making it uncharged, thus not capable of ionizing other molecules in its pathway for it to not produce an anode signal?

 

[Jepstein30]

For #47 in PS: What particle would produce the largest anode signal when transversing a proportional chamber with an initial speed of 99% that of light?
Why is the answer an alpha (helium) particle? The answer says it's due to it's +2e charge; however, doesn't it have 2 protons and 2 neutrons, making it uncharged, thus not capable of ionizing other molecules in its pathway for it to not produce an anode signal?

2 protons + 2 neutrons = +2 charge

I think you're confusing neutrons with electrons..

 

[danny89]

2 protons + 2 neutrons = +2 charge

I think you're confusing neutrons with electrons..

I forgot to mention if the alpha particle assumes the uncharged Helium atom of 2 protons, 2 neutrons and 2 electrons, unless the alpha particle is naturally charged.

 

[Jepstein30]

I forgot to mention if the alpha particle assumes the uncharged Helium atom of 2 protons, 2 neutrons and 2 electrons, unless the alpha particle is naturally charged.

An alpha particle is a helium nucleus, not a helium atom.

So just 2 protons and 2 neutrons. No electrons.

 

[bluebillion]

that vole question was really stupid. the passage stated that it happened in US Southwest, and went away in the winter. I didn't know what a vole was and guessed snake based on that information.

Are we supposed to know these ambiguous names for animals for the MCAT? I would hate to have a question like this on my exam

 

[orangeman25]

I have a question on the PS section, question 19: "What would be the value of the gravitational acceleration at the surface of a planet that has twice the mass and twice the radius of Earth?"

I set mg=GMm/r^2 . I cancelled m on both sides (the m refers to this unknown planets mass I thought because mg is the gravitational force on the surface of this planet). Since now I have g=GM/r^2, I thought I didn't have to take into consideration the difference in masses between earth and the unknown planet because only one mass, M (earths mass) remains in the equation.

The answer is that if both mass and radius are doubled, then g would be one half as large as that on earth. Can someone explain this?

 

[orangeman25]

One more question, regarding item 123 on BS.

What does this sentence mean to you guys: "Strain B grows slower than strain A and is also resistance to streptomycin"

Because they use the word "also", it makes me believe that they are saying that strain A is also resistant to streptomycin. If they didn't use the word "also", it would make more sense. Anyone think this also?

 

[sazerac]

I have a question on the PS section, question 19: "What would be the value of the gravitational acceleration at the surface of a planet that has twice the mass and twice the radius of Earth?"

I set mg=GMm/r^2 . I cancelled m on both sides (the m refers to this unknown planets mass I thought because mg is the gravitational force on the surface of this planet). Since now I have g=GM/r^2, I thought I didn't have to take into consideration the difference in masses between earth and the unknown planet because only one mass, M (earths mass) remains in the equation.

The answer is that if both mass and radius are doubled, then g would be one half as large as that on earth. Can someone explain this?

The gravitational force F = G M1 M2 / r^2.

When dealing with planet earth, one object tends to be small (m) and the earth tends to be massive (M), so we often rewrite it as F = G M m / r^2.

Also, the mass of the earth tends to be a constant, and so does the distance between the objects (most objects in everyday life sit at the surface of the earth), so G and M and r are constant. Thus we are left with F = m (G M/r^2). We can replace (G M/r^2) with "g" and rewrite the whole equation as F = mg.

But now we have a question that asks about some other planet besides earth. So we can't really use F=mg because that is so earth specific. The more general equation is still applicable though. F = GmM/r^2. What if we replaced M by a value that was twice as large? What if we also replaced r with a value that is twice as large? What would be the force between the object and the planet then?

 

[stuw]

For #26 for PS, I always thought that the EQ point was the pH middle point of where the SB (or SA) pass the capacity and when the pH level begins to level off. Why is it that we're able to use an indicator for the steep incline? Is it because we simply want to GENERALLY know when our WA is turning basic?

*edit* also, could someone further explain 28? I picked 25 ml, but only because the half eq point didn't fall on 7. Could someone explain why 7 isn't the correct answer and 25 is? thanks!

 

[stuw]

^bump

 

[Thisisthelife]

For #26 for PS, I always thought that the EQ point was the pH middle point of where the SB (or SA) pass the capacity and when the pH level begins to level off. Why is it that we're able to use an indicator for the steep incline? Is it because we simply want to GENERALLY know when our WA is turning basic?

*edit* also, could someone further explain 28? I picked 25 ml, but only because the half eq point didn't fall on 7. Could someone explain why 7 isn't the correct answer and 25 is? thanks!

Hello,

When approaching titrations between a SA and SB the most important thing to remember is that the pH is 7 when the moles of the acid and base are equal. If you look at table 1, titration 3 you will see that both NaOH and HCl have the same molarity (0.0010 M). You also see that 25mL of analyte (in this case HCl) was added. Since the molarities are equal the number of moles is equal at the same volume. In this case that volume is 25 mL.

 

[inasensegone]

I'm still not entirely sure what to make of the particle accelerator physics passage. I got super lucky with some educated guesses here, but I feel like I lack an understanding of the experiment.

Does anyone know why the electrons are collected at the anode? Aren't electrons supposed to go from Anode to Cathode?

On the other hand, I thought this was the easiest biology section of all the tests so far, so that was kind of a nice trade I suppose.

 

[Slave to the Game]

I'm still not entirely sure what to make of the particle accelerator physics passage. I got super lucky with some educated guesses here, but I feel like I lack an understanding of the experiment.

Does anyone know why the electrons are collected at the anode? Aren't electrons supposed to go from Anode to Cathode?

On the other hand, I thought this was the easiest biology section of all the tests so far, so that was kind of a nice trade I suppose.

Electrons go from anode to cathode. In this case, I don't think the electron source is the cathode, it's the ionizing gas. So the electrons collect at the anode so that they can then go to the cathode.

 

[inasensegone]

Electrons go from anode to cathode. In this case, I don't think the electron source is the cathode, it's the ionizing gas. So the electrons collect at the anode so that they can then go to the cathode.

Ahhhhh... good point, thank you for the feedback!

 

[Karamsoft]

For question 9: I know the answer is D, however, I don't understand how solid nitrogen is expected to have a high energy density when compared to methanol (which , in addition to covalent bonding, has a H-bonding)? If you have the advantage of being stabilized by forming H-bonds, would that mean that your energy density is increased as a result (ie. it follows that you might have a higher boiling point)??

Thanks

 

[stester77s]

The passage author implies that environmental scientists are particularly interested in: A) the willingness of the military to allow research on its bases.
Passage information does not reveal any particular interest by scientists toward the willingness of the military to allow research on its bases. This willingness is simply reported as the military’s desire to comply with the Endangered Species Act and the military’s interest in delisting the tortoise as a threatened species so war games can resume in the desert tortoise sanctuary.


B) new discoveries about the habits of the desert tortoise.
The passage does not indicate any particular interest by scientists in new discoveries about desert tortoises, only that broad conclusions about the species are impossible to obtain from local studies.


C) a lack of access to data collected by spy satellites.
Access to data is restricted but not lacking: “Only scientists with security clearances can see these data.” The passage does not indicate that restricted access is an issue of any particular interest to scientists.


D) the role of space-based sensors in future research.
The passage author states: The [desert tortoise] study’s importance lies in the use of advanced intelligence-gathering tools to examine the environment.”


AAMC says D. Is that a joke? Environmental scientists are interested in desert tortoises, which is why they are the focus of one of the projects being studied. Maybe a small subgroup of environmental engineers or others will be more interested in this potential technology for future research. And yes, the "main idea" of the passage was about the space probes, but that is not relevant to the question. The question asks what environmental engineers are interested in. Environmental engineers' work is not dedicated to speculating about a small potential future technology in their field. They are focused on environmental issues, like those faced by the desert tortoise.

 

[ldiaz29]

#86 am I a total ***** for not knowing what the difference between astronomy and astrology?

 

[Slave to the Game]

#86 am I a total ***** for not knowing what the difference between astronomy and astrology?

Not really, but considering you're taking your MCATs soon you should know the difference.

The passage author implies that ...They are focused on environmental issues, like those faced by the desert tortoise.

This question was kind of difficult for me as well, and it doesn't get much easier on the real thing. Sorry I couldn't help, but you're not alone in thinking this is WTF. Best of luck, and try to think like the test writers (i.e. the most obvious answer is probably not correct if the question says 'implies')

 

[dudewheresmymd]

Why is chloroform considered non-polar here? Doesn't it have a net dipole?

 

[Saxappeal1]

I guess they wanted to exhibit the typical "two of the answers are right but one is more right" type scenarios here, while it is clear that CHCl3 has a net dipole, it is nothing compared to CH3COOH's dipole. But that's just my take on it.

 

[Slave to the Game]

I guess they wanted to exhibit the typical "two of the answers are right but one is more right" type scenarios here, while it is clear that CHCl3 has a net dipole, it is nothing compared to CH3COOH's dipole. But that's just my take on it.

This. Also it's an acid by name, that should've stuck out. I also used the fact that DCM, while "polar", is used to dissolve organic/nonpolar substances. IMO they're too small to be really polar, the distance between the dipoles is not strong enough - there's an equation from PS that has something along the lines of distance between dipoles x charge = strength of dipole. Apologies if unclear, but hopefully it gets you in the right direction.

 

[sunshine02]

For question #132, why is the answer A?

If more NE is in the synaptic cleft it will continually stimulate the adrenergic receptors, but wouldn't that DECREASE the sympathetic response since it is continually being stimulated (more depolarization and thus not enough time to completely repolarize). If something doesn't repolarize, how can it generate another response? The increase in amount of NE in the synaptic cleft only prevents it from being repolarized thus it is not able to respond to incoming action potentials.
I'm pretty sure I remember another AAMC question that asked a very similar question involving Acetylcholinesterase inhibitors or something like that and the answer was the complete opposite of this one.
Can someone please explain? Thanks!

 

[Thisisthelife]

View attachment 182299

Why is chloroform considered non-polar here? Doesn't it have a net dipole?

Even if it is. You should simply think acidic=not dissolving a hydrocarbon. Hydrocarbon=not dissolving an acid. Like dissolves like and an acid is DEFINITELY not going to dissolve the hydrocarbon thats all there is to it.

 

[BornToLead]

Please explain me this.
My thought process for choosing B was that, since the compound has lost both of its H+, the
pH must be low cuz of the H+ floating around.

 

[bleach121]

View attachment 184594

Please explain me this.
My thought process for choosing B was that, since the compound has lost both of its H+, the
pH must be low cuz of the H+ floating around.

You have to remember that an amino acid exists either in its zwitterionic state for an aqueous environment (where the C terminal is deprotonated and the N terminal is protonated; hence a net zero charge) or a neutral state for a lipid environment (where the C terminal is protonated and the N terminal is not).
For the given amino acid, the only way to deprotonate the C terminal is to have a pH above the C terminal's pKa (given as 2.35) and to deprotonate the N terminal from NH3+ to NH2 is to have a pH greater than the N terminal pKa (given as 9.87). So overall you would need a pH greater than 9.87 to have the AA exist with both the N terminal and C terminals deprotonated.

 

[bleach121]

Can someone tell me where my thought process was wrong for question #50 for PS:

I understand the calculation, but I tried answering it conceptually and confused myself. I thought that for each increase in intensity by a factor of 10, the intensity level increases by 10. So since the Intensity level was 120 dB, I thought that the intensity must have been 10^12. I'd appreciate it if someone could explain to me what I'm missing. Thanks.

 

[Oh_Gee]

20. got this wrong cause from the passage, i thought it was just talking about the projectile getting to its max height. passage never mentioned it falling down but i guess i should assume so? my experience from VR told me to take the passage as literally as i could and not assume anything if not asked to. wtf AAMC?
also they admit in the answer explanation that the given answer is not entirely complete. would an answer choice along the lines of "170hz - frequency heard just before it reaches its peak" be better? since magnitude doesn't take + or - into account

21. just curious about this. what does give shrapnel its momentum? i'm assuming it's just the explosive force of the chemical reaction. is there any way we could calculate this within MCAT boundaries?

103. i chose h-bond because i remember my high school bio teacher telling us that when asked any biology question, always answer H-bond and you will most likely be right. this has served me well for the most part
so does h-bond always play a bigger role in BP than the MW? if there was a huge difference in size, such as BP of 1 propanol vs a 20 carbon straight chain alkane, the 20 carbon alkane would have the highest BP based on its MW right?

111. lol took 1 look at this passage and said nope. went back to it after everything else and had 20 minutes left
anyways, how much specificity of antibodies should we assume? i know IgE and IgG have different specialties but how are we supposed to know? i just guessed the AAMC would expect us to that antibodies are specific for 1 type of antigen only so would this antibody react with different hantaviruses? same glycoprotein???

 

[Shirafune]

20. got this wrong cause from the passage, i thought it was just talking about the projectile getting to its max height. passage never mentioned it falling down but i guess i should assume so? my experience from VR told me to take the passage as literally as i could and not assume anything if not asked to. wtf AAMC?
also they admit in the answer explanation that the given answer is not entirely complete. would an answer choice along the lines of "170hz - frequency heard just before it reaches its peak" be better? since magnitude doesn't take + or - into account

21. just curious about this. what does give shrapnel its momentum? i'm assuming it's just the explosive force of the chemical reaction. is there any way we could calculate this within MCAT boundaries?

103. i chose h-bond because i remember my high school bio teacher telling us that when asked any biology question, always answer H-bond and you will most likely be right. this has served me well for the most part
so does h-bond always play a bigger role in BP than the MW? if there was a huge difference in size, such as BP of 1 propanol vs a 20 carbon straight chain alkane, the 20 carbon alkane would have the highest BP based on its MW right?

111. lol took 1 look at this passage and said nope. went back to it after everything else and had 20 minutes left
anyways, how much specificity of antibodies should we assume? i know IgE and IgG have different specialties but how are we supposed to know? i just guessed the AAMC would expect us to that antibodies are specific for 1 type of antigen only so would this antibody react with different hantaviruses? same glycoprotein???

20. Point is that none of the other answers make sense. At the object's max height, it's velocity should be zero. And by the Doppler Effect, if there the object is not moving, then there is no difference in the frequency emitted and the frequency detected. Hence, it needs to be zero at some point. B) is incorrect because the object is accelerating due to gravity and because velocity changes, the frequency shift cannot be constant. C) is incorrect because the magnitude of the frequency shift cannot increase to zero. D) is incorrect because after the object has reached its maximum height, it velocity increases as it falls back to Earth. Therefore, the frequency shift decreases (the object's speed falls as it approaches its max height), reaches zero, and then increases (as the object picks up speed as it falls).

21. You might be given the force generated by the explosion and the length of the explosion. You would be able to calculate impulse with this information.

103. H-Bonding does not always play a bigger role in BP than MW. AAMC is not going to ask you to compare BP for two compounds with very different carbon backbone lengths. Even if they did, the passage would likely provide the necessary supplemental information to answer the question.

111. The passage provides evidence that it would not be A) because all the experiments are centered around pulmonary tissue and function. Experiment 1 uses this reasoning. The body responds to pathogens by creating antibodies. If there are antibodies in the blood, then there should be a reaction between the sera and a library of known viruses and bacteria. So you know this should be an antibody reaction to something. D) is obviously not correct now. C) is incorrect because nothing suggests this is an autoimmune issue. And like I said, kidney disease hantavirus is not likely to cause significant pulmonary complications, or at least not suggested by this passage. Antibodies do have a high level of specificity, but if the epitopes are very similar, then there can be comparable levels of affinity between two related epitopes.

 

[Shirafune]

Can someone tell me where my thought process was wrong for question #50 for PS: View attachment 184750

I understand the calculation, but I tried answering it conceptually and confused myself. I thought that for each increase in intensity by a factor of 10, the intensity level increases by 10. So since the Intensity level was 120 dB, I thought that the intensity must have been 10^12. I'd appreciate it if someone could explain to me what I'm missing. Thanks.

Right. You answered your own question. I0 is 10^-12 and 120dB louder than this would be an intensity of 10^0. You probably just didn't pay close enough attention. You could have also just solved for I algebraically.

 

[Oh_Gee]

20. Point is that none of the other answers make sense. At the object's max height, it's velocity should be zero. And by the Doppler Effect, if there the object is not moving, then there is no difference in the frequency emitted and the frequency detected. Hence, it needs to be zero at some point. B) is incorrect because the object is accelerating due to gravity and because velocity changes, the frequency shift cannot be constant. C) is incorrect because the magnitude of the frequency shift cannot increase to zero. D) is incorrect because after the object has reached its maximum height, it velocity increases as it falls back to Earth. Therefore, the frequency shift decreases (the object's speed falls as it approaches its max height), reaches zero, and then increases (as the object picks up speed as it falls).

21. You might be given the force generated by the explosion and the length of the explosion. You would be able to calculate impulse with this information.

103. H-Bonding does not always play a bigger role in BP than MW. AAMC is not going to ask you to compare BP for two compounds with very different carbon backbone lengths. Even if they did, the passage would likely provide the necessary supplemental information to answer the question.

111. The passage provides evidence that it would not be A) because all the experiments are centered around pulmonary tissue and function. Experiment 1 uses this reasoning. The body responds to pathogens by creating antibodies. If there are antibodies in the blood, then there should be a reaction between the sera and a library of known viruses and bacteria. So you know this should be an antibody reaction to something. D) is obviously not correct now. C) is incorrect because nothing suggests this is an autoimmune issue. And like I said, kidney disease hantavirus is not likely to cause significant pulmonary complications, or at least not suggested by this passage. Antibodies do have a high level of specificity, but if the epitopes are very similar, then there can be comparable levels of affinity between two related epitopes.

well for 20, what if the question stem did say "only consider the flight of the projectile from the ground to max height" would my answer be right then?

 

[Shirafune]

well for 20, what if the question stem did say "only consider the flight of the projectile from the ground to max height" would my answer be right then?

Yes. That would be the best answer.