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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[G1SG2]

If both side chains have been deprotonated, the pH of the solution would have to be greater than the pKa of both chains. If it was between 6.11 and 9.81, the chain with pKa of 2.35 would be deprotonated, but the chain with pKa of 9.87 would be protonated.

Thanks.

 

[SuperSaiyan3]

Honestly though, having a clue as to what voles are is how I got the answer.

Same here. I just recalled that in some Shakespearean play that I read in English class back in high school mentioned voles. And you know how in those Shakespeare books they have translations (of English to English... ridiculous) and they had one for voles. I just recalled that from like five bazillian minutes ago in my life and got the answer.

 

[maroon95]

pookiez88 wrote

Here's another one:

Alanine has two pKa values: one at 2.35 and one at 9.87. At what pH would alanine exist primarily in the form of a deprotonated COOH group, giving CO2- (net negative charge)? The answer is above 9.87 (choice D) Why isn't it between 6.11 and 9.87? I mean at first I thought it should've been above 6.11, which is it's pI. Isn't that the rule? That the amino acid would be primarily deprotonated at a pH above it's pI?[/QUOTE]


--
my thoughts on biochem

the answer is "above 9.87"
it's above that pH value alanine would primarily exist.
at very low pH values (say 1-2), alanine would be in the form

+H3N
HC-COOH
CH3

at pK1 (2.35) value, the acidic proton of the carboxyl group would deprotonate first. at pK2, the second acidic proton of the amine group would then deprotonate to yield
H2N
HC-COO-
CH3

for more reading, please consult textbook by Lehninger (chapter 3.1 page 83 of the 5th edition)
http://www.whfreeman.com/lehninger/

 

[vandyam]

Didn't see this mentioned here but -- #125 on the bio section is wrong, right? The explanation says that the answer is B (what I put), but it has D highlighted as the right answer (and, quite frankly the answer makes no sense as it is opposite the answer I think it should be). Am I right, or am I just reading it wrong/losing my mind?

 

[Hemichordate]

Answer should be D (at least that's what it shows on mine)

 

[vandyam]

Answer should be D (at least that's what it shows on mine)

Yeah, but here are the answer choices that are relevant:

B) Strain A grows faster than strain B and strain A is also resistant to streptomyosin.

D) Strain B grows slower than strain A and is also resistant to streptomyosin.


And here is the answer explanation:

The question asks the examinee to identify the explanation that best accounts for the results shown in Figure 1. In Figure 1, the slope of the line indicating the exponential growth phase of Strain A is significantly steeper than the slope of the line indicating the exponential growth phase of Strain B. This implies that Strain B grows more slowly than Strain A. The figure also shows that Strain B grows equally well in the presence and absence of streptomycin, indicating resistance to streptomycin, whereas the growth of Strain A is stunted in the presence of streptomycin, indicating streptomycin sensitivity. Of the options given, only D indicates that Strain B grows more slowly than Strain A and that Strain B is resistant to streptomycin. Thus, D is the best answer.

I think I just realized after typing it out, that the answer choices are referring to the the first strain given, not the last. So answer B is saying that A is resistant to streptomyosin (I read it as B is resistant to streptomyosin), and for answer D it is saying that B is resistant to streptomyosin (again, opposite of what I was thinking). I guess I was just reading the answer choices wrong. Wow...I am so over the MCAT.

 

[maroon95]

so could someone please post answer to #124 (h. pylori) ? thank you.
A) No, because the patient could have been exposed to H. pylori and eliminated it.
B) No, because the test could not detect different strains of H. pylori
C) Yes, because the patient must have cells of H. pylori present to produce antibodies
D) Yes, because virtually all patients who have ulcers have H. pylori infections

The reason I got this right was because of a past AAMC. I remember an old passage on H. pylori saying that not everyone who was infected necessarily got stomach ulcers because they could have fought off the infection. I remembered that, and then picked A. Kind of a dumb question.

 

[ezsanche]

so could someone please post answer to #124 (h. pylori) ? thank you.
A) No, because the patient could have been exposed to H. pylori and eliminated it.
B) No, because the test could not detect different strains of H. pylori
C) Yes, because the patient must have cells of H. pylori present to produce antibodies
D) Yes, because virtually all patients who have ulcers have H. pylori infections

Elisa test is used to detect antibodies that are made by the b cells. Antibodies are made only if an individual is infected with the pathogen.

So a positive elisa test will only tell you if a person is infected or was infected by h. pylori.

Now the question is asking you if a positive elisa means if a person had a ulcer. The answer is NO because just because you determined a person had H. pylori doesn't mean he had ulcers.

 

[maroon95]

can you just post the answer from AAMC? i have misplaced the key. thanks.


and besides, i think your reasoning is flawed.
h. pylori causes ulcer all the time
95% of ppl having ulcers also have bacteria h. pylori in their body.

Elisa test is used to detect antibodies that are made by the b cells. Antibodies are made only if an individual is infected with the pathogen.

So a positive elisa test will only tell you if a person is infected or was infected by h. pylori.

Now the question is asking you if a positive elisa means if a person had a ulcer. The answer is NO because just because you determined a person had H. pylori doesn't mean he had ulcers.

 

[thebillsfan]

Hey folks,

just took this test today and the curve was a beast.

quick ? from the ps:

If a monolayer of water molecules is formed over an organic oil, can Avogadro’s number be calculated using the method described in experiments 1 and 2? A
) Yes, because the height of the water molecule can be determined B
) Yes, because the volume of the monolayer can be determined C
) No, because water will disperse across the top of the organic oil D
) No, because water molecules are not cylindrical in shape
To determine Avogadro’s number using the oleic acid method, the oleic acid molecules were considered cylindrical in shape. The same method could not be used if a monolayer of water molecules is formed over an organic oil because the water molecules are not cylindrical in shape. Thus, D is the best answer.

D is the right answer, but I'm not sure why A cannot be correct. Yeah, the passage said the molecules were assumed to be cylindrical, but I dont understand why that was necessary for the determination of avogadro's number. Bottom line, if you can figure out the height and know the volume of water, then youd be finding the same data you did with oleic acid. So why cant you use water?

 

[thebillsfan]

and one from the VR:

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.”


I dont agree with D being the right answer. Scientists care about the science. It's not true that:
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.


The passage DOES say that scientists were interested in knowing more about desert tortoises, their habitat, that they're more likely to be found in certain environments. This doesnt make any sense. However, I realize there's no point in me refuting this answer because it IS the answer. Whereas I can bash EKs answer, I can't bash AAMCs--because even if they are (imo) incorrect, theyre the credited response.

 

[wanderer]

and one from the VR:

The passage author implies that environmental scientists are particularly interested in: A
) the willingness of the military to allow research on its bases.

B
) new discoveries about the habits of the desert tortoise.

C
) a lack of access to data collected by spy satellites.

D
) the role of space-based sensors in future research.



The passage DOES say that scientists were interested in knowing more about desert tortoises, their habitat, that they're more likely to be found in certain environments. This doesnt make any sense. However, I realize there's no point in me refuting this answer because it IS the answer. Whereas I can bash EKs answer, I can't bash AAMCs--because even if they are (imo) incorrect, theyre the credited response.

The main idea of the passage is that military technology can tell us a lot about the environment (that civilian technology can't). The anecdotes involving tortoises are merely used as examples, but not as the main idea. ("The unclassified report gives a flavor of the data obtainable from spy technology", in other words the tortoise data is the flavor, and the potential for other research is the main course) Also notice how the paragraph talks about the habitat of tortoises, but the answer choice refers to the habits of tortoises. This however is a minor point, even if it had used the word habitat it would still be wrong. Just be on the lookout for words that sound similar but have different meanings.

 

[Kanye West]

Hey folks,

just took this test today and the curve was a beast.

quick ? from the ps:

If a monolayer of water molecules is formed over an organic oil, can Avogadro’s number be calculated using the method described in experiments 1 and 2? A
) Yes, because the height of the water molecule can be determined B
) Yes, because the volume of the monolayer can be determined C
) No, because water will disperse across the top of the organic oil D
) No, because water molecules are not cylindrical in shape
To determine Avogadro’s number using the oleic acid method, the oleic acid molecules were considered cylindrical in shape. The same method could not be used if a monolayer of water molecules is formed over an organic oil because the water molecules are not cylindrical in shape. Thus, D is the best answer.

D is the right answer, but I'm not sure why A cannot be correct. Yeah, the passage said the molecules were assumed to be cylindrical, but I dont understand why that was necessary for the determination of avogadro's number. Bottom line, if you can figure out the height and know the volume of water, then youd be finding the same data you did with oleic acid. So why cant you use water?

This was a weird one, I am not sure why A can't work. Also why is C wrong? Is it because the water is insoluble in the organic so it will just "stand"?

 

[Kanye West]

BS#121

Which of the following is the most plausible explanation for the fact that the saponification of the triacylglycerol in the passage resulted in four different fatty acid salts?

Answer: D - One of the fatty acid salts was unsaturated, and a small percentage isomerized under reaction conditions

How does this work? Even if a double bond isomerized (something like E or Z right?), you would still have 3 fatty acid chains, R1, R2, R3...

I see how this would make sense if you had more than one triacylglycerol, but the passage states there is only one: "a pure triacylglycerol"

Can someone explain this please??

 

[burningheat]

yeah... I knew deep down in my heart that it would be the right answer.. but my inner conscience got the best of me... but at least now I can sleep in peace without knowing that I could be capable of intentionally making a healthy person sick... who knows.. maybe he/she would have died from the infection and what would I say to the family? How could I live with myself??

Oh the tragedy!!

it has been posted twice alrdy, but probably the reason they used this is because this is EXACTLY what barry marshall (http://en.wikipedia.org/wiki/Barry_Marshall) did to prove that the bacterial caused stomach ulcer! AND got a nobel prize for it.


I dunno why but a few yeasr ago i was forced to read an article he wrote, kind of funny that this exact question was on the test, i thought of him immediately

 

[ezsanche]

BS#121

Which of the following is the most plausible explanation for the fact that the saponification of the triacylglycerol in the passage resulted in four different fatty acid salts?

Answer: D - One of the fatty acid salts was unsaturated, and a small percentage isomerized under reaction conditions

How does this work? Even if a double bond isomerized (something like E or Z right?), you would still have 3 fatty acid chains, R1, R2, R3...

I see how this would make sense if you had more than one triacylglycerol, but the passage states there is only one: "a pure triacylglycerol"

Can someone explain this please??

No you wont!!!!

Read the answer a SMALL PERCEntage ISOMERIZED

So lets say the Fatty acids chains are R1, R2, R3 and about 10 percent ( i consider this to be small... but the point is that only a small percentage isomerize so you are still left with a portion of the other chain) of R3 isomerize to R4. So you will have R1, R2, R3 and R4

 

[NVswmmr]

So I got this question right, but by only eliminating C and D because they had the same sequence at the end. However, why are C and D wrong? Is it only because they fail to mention the fallopian tubes?

The normal path of sperm movement from the male testis to the point of fertilization in the female is: A
) epididymis, vas deferens, urethra, vagina, cervix, uterus, fallopian tube.
The question asks the examinee to identify the correct order of structures through which sperm cells travel from the male testis to the point of fertilization in the female. As sperm cells leave the testis they travel through the epididymis to the vas deferens and into the urethra. The sperm then enter the female’s vagina, travel through the cervix and uterus, and enter the fallopian tube, where fertilization most commonly takes place. Of the options listed, only A correctly identifies both the structures and the order. Thus, A is the best answer.


B
) epididymis, vas deferens, ureter, cervix, uterus, fallopian tube. C
) epididymis, vas deferens, urethra, vagina, uterus, ovary. D
) interstitial cells, epididymis, vas deferens, vagina, uterus, ovary.

 

[wait4me]

#121 bio. A stable cell that will not undergo division again is in this stage: the answer is G1 but I thought G1 was a restriction point where they were committed to undergo division?

 

[ratatat]

So I got this question right, but by only eliminating C and D because they had the same sequence at the end. However, why are C and D wrong? Is it only because they fail to mention the fallopian tubes?

The normal path of sperm movement from the male testis to the point of fertilization in the female is: A
) epididymis, vas deferens, urethra, vagina, cervix, uterus, fallopian tube.
The question asks the examinee to identify the correct order of structures through which sperm cells travel from the male testis to the point of fertilization in the female. As sperm cells leave the testis they travel through the epididymis to the vas deferens and into the urethra. The sperm then enter the female’s vagina, travel through the cervix and uterus, and enter the fallopian tube, where fertilization most commonly takes place. Of the options listed, only A correctly identifies both the structures and the order. Thus, A is the best answer.


B
) epididymis, vas deferens, ureter, cervix, uterus, fallopian tube. C
) epididymis, vas deferens, urethra, vagina, uterus, ovary. D
) interstitial cells, epididymis, vas deferens, vagina, uterus, ovary.

I believe so, because they ask about the path to fertilization. Fertilization occurs in the fap' tubes, so if the answer doesn't include them, it's wrong.

 

[doremi2010]

#129 knowing the specifics of the reaction mechanism is not necessary, but when do grignard reagents attack alcohols? I don't ever remember learning this and cannot find info about it in any of my study books...

 

[wanderer]

#129 knowing the specifics of the reaction mechanism is not necessary, but when do grignard reagents attack alcohols? I don't ever remember learning this and cannot find info about it in any of my study books...

Grignards are very strong _____
Alcohols are mild _____
Therefore they will undergo _____________ instead of substitution.

 

[girlspowerss]

On AAMC 10, question 28 asks where on the graph the concentraions equal each other... I thought that occurs at the half equivalence point, which is around 7mL. Howeve,r the answer is 25mL at a pH of 7.
Isnt the half equivalence the point where pH = Pka because acid = base? So wouldnt that be the point where the concentrations equal each other? Im confused
Thanks

 

[Greenbayslacker]

.

 

[wanderer]

PS #40

i know i got it right, but how was i supposed to arrive at this answer?

You can think about it in terms of, "Which of the following solvents is least like the others?" Benzene and diethyl ether are common nonpolar solvents, as is chloroform (you might think that chloroform is polar because the Cl atom is polar, but it's still a nonpolar solvent). Acetic acid is polar because of the carboxyl group and there are only 2 carbons.

BS #109

no idea for this one.. oh yeah, and also what is inductive effect?
See my posts on 7/15 and the responses to them.
BS #128

ANOTHER solvent problem?? don't get this one either..
It's not really a solvent problem if you think about it, it's a functional group reactivity problem. You never want solvents reacting. Since a Grignard reagent is a very strong nucleophile it will react even with weak electrophiles (acetone and acetate, which both contain carbonyl groups) and will react with alcohols because alcohols are somewhat acidic and Grignards are very basic.

BS #134

according to the passage, any NE not taken up will be destroyed by COMT -- so if reabsorption is blocked by the drug, wouldn't COMT just destroy the NE, thereby decreasing any stimulation that might occur??

BS #143

yet another one i have no idea about.. i think exam krackers is missing some stuff


thanks so much for any help! as soon as i get a job i am donating to SDN, the help on these forums has been invaluable

~

 

[ronaldo23]

hey guys, a little confused about the titration question- number 28. The explanation says that at the equivalence point [H30+]= [OH-] . But I thought the [HA]=[A-] at the HALF-equivalence point (hence pka=pH at this point, as the log of 1=0), and that at the equivalence point is 100% [A-]....am I missing something?

 

[supras2kracer]

hey guys, a little confused about the titration question- number 28. The explanation says that at the equivalence point [H30+]= [OH-] . But I thought the [HA]=[A-] at the HALF-equivalence point (hence pka=pH at this point, as the log of 1=0), and that at the equivalence point is 100% [A-]....am I missing something?

haha yeah this one threw me off as well. Think about it this way. What is the conjugate base and what is the titrant? The conjugate base is OAc- while the titrant is OH-

So at pH=7 the H+ (also referred to as H30+) concentration is equal to the OH- that comes from the NaOH.

 

[supras2kracer]

hi guys, sorry i have so many questions but i wanted to get all of the ones i got wrong nailed down since this is my last full length (1 week til exam day!!). some of these have been answered already but the explanations still don't make sense to me

BS #134

according to the passage, any NE not taken up will be destroyed by COMT -- so if reabsorption is blocked by the drug, wouldn't COMT just destroy the NE, thereby decreasing any stimulation that might occur??

BS #143

yet another one i have no idea about.. i think exam krackers is missing some stuff


thanks so much for any help! as soon as i get a job i am donating to SDN, the help on these forums has been invaluable

for 134: enzymes can only work so fast. This means that while they're working a lot of the accumulating NE is still going to be acting on the post synaptic neuron.

for 143: first, you have to realize that it's an amino acid. look at the page of examkrackers that shows the zwitter ion. The amino acid exists in three confirmations. One has an NH3 and COOH (most acidic confirmation), second confirmation still has the NH3 but has a COO-, and the most basic confirmation has NH2 and COO- so you'd expect a pH>7.

Hope this helps. (p.s. I also missed all of those problems!)

 

[supras2kracer]

check out the aamc 10 thread. Just answered the same question

 

[Insulinshock]

BS 128:

For this question you need to know that Grignard reagant cannot undergo their normal reaction in protic solvents. Of the options, diethyl either is non-polar, and thus the right answer.

If you look at all the answers 3 of them are polar and 1 (diethyl ether) is not. This should signal to you the right answer as well.

I took this test today and got a 13 on the BS!!

 

[Greenbayslacker]

.

 

[lDanny]

haha yeah this one threw me off as well. Think about it this way. What is the conjugate base and what is the titrant? The conjugate base is OAc- while the titrant is OH-

So at pH=7 the H+ (also referred to as H30+) concentration is equal to the OH- that comes from the NaOH.

man that one got me.. I just looked at and assume it was the conj. acid and base, instead of seeing that they meant neutral.. tricky!

 

[girlspowerss]

where can i find that?

 

[supras2kracer]

The third stickie on the MCAT study question forum has a link to each of the specific practice test threads. It's been pretty helpful so you should check it out.

For a good explanation check out the thread but basically it's a tricky question. It asks when the OH concentration is equal to H+. The OH is from the NaOH, NOT the conjugate acid.

 

[puffylover]

My Question:

Intermolecular Bonding is considered a weak intermolecular interaction?!

What bonding accounts for the expected increase in energy density of solid nitrogen as compared to methanol? A
) Solid nitrogen contains covalent and ionic bonds; methanol contains only weak ionic bonds. B
) Solid nitrogen contains covalent and ionic bonds; methanol has covalent bonds within each molecule and weak van der Waal’s interactions between molecules. C
) Solid nitrogen contains only covalent bonds; methanol contains only weak ionic bonds. D
) Solid nitrogen contains only covalent bonds; methanol has covalent bonds within each molecule and weak intermolecular interactions.
Solid nitrogen contains only covalent bonds. Methanol contains only covalent bonds within each molecule but is capable of intermolecular hydrogen bonding because of the –OH group. Thus, D is the best answer.

 

[puffylover]

My Question:

How do you determine the oxidation state of the metal in a coordination complex???

Solution

Mark The oxidation state of copper in going from the penny to the waste mixture changes from: A
) 0 to +2.
Copper metal in the penny has the oxidation state of 0. According to the passage, the waste mixture contains Cu(NH3)42+(aq). The oxidation state of copper in this complex ion is +2. In going from the penny to the waste mixture, the oxidation state of copper changes from 0 to +2. Thus, A is the best answer.


B
) 0 to +1. C
) +1 to 0. D
) +2 to 0.

 

[puffylover]

does anyone have the equation that the solution for this question is referring to?

do you just set centripetal force equal to the force of the magnetic field?

mv2/r=qvB?

Item 45

Solution

Mark Why are curved particle trajectories through stacks of ionization chambers preferable to straight ones? A
) Curved trajectories require longer travel times, providing more time for data analysis. B
) Straight-line trajectories would produce too few anode signals to define tracks precisely. C
) The radius of curvature can be used to help identify the particle that produced the track.
Charged particles in motion constitute a current, and freely moving charges are deflected by a magnetic field into a curved path. The amount of curvature depends on the charge and mass of each incoming particle and can be effectively used to distinguish different species of particles from one another. Thus, C is the best answer.


D
) Neutron trajectories can be immediately distinguished from those of other particles.

 

[puffylover]

Why is D wrong? Is that an approximation for a real gas?

tem 51

Solution

Mark The term “ideal gas” refers to a gas for which certain assumptions have been made. Which one of the following assumptions applies to an ideal gas? A
) The law PV = nRT2 is strictly obeyed. B
) Intermolecular forces are infinitely large. C
) Individual molecular volume and intermolecular forces are negligible.
It is assumed that the molecules in an ideal gas have no volume and that there are no interactions between the molecules. Thus, C is the best answer.


D
) One mole occupies a volume of 22.4 L at 25°C and 1 atm pressure.

 

[puffylover]

why can you recrystallize?

Item 101

Solution

Mark 1-Propanol and 1,2-ethanediol can be most efficiently separated by which of the following techniques? A
) Extraction with ethanol B
) Extraction with water C
) Recrystallization D
) Fractional distillation
According to Table 1,1-propanol and 1,2-ethanediol are liquids under ordinary conditions with different boiling points and both are highly soluble in water. Both are also very soluble in ethanol. The compounds could be most efficiently separated by fractional distillation. Thus, D is the best answer.

got the answer. for anyone who has the same question: recrystallization is based on solubility. i dunno why i mixed it up with fp/mp

 

[schlieren]

For the "vole" question (# 116), there is one more hint that so far is ignored in discussion. The disease came in spring 1993 and subsided in winter 1993. So it is likely carried by a warm-blooded host that dies in winter. I did not know vole either, but guess right by this hint.

 

[rls303]

Hi everyone,
Sorry this is kind of an elementary question regarding charges of group VIA.
Item2:
In the solution it says Sulfur has a 2- charge, when it is with ZnS, is this also the charge of the other elements in that group?

Item 7:
Okay so why exactly will the one with the lower Ksp work better for this set up? Why would the copper work better?

Thanks in advance!

 

[rls303]

Why is D wrong? Is that an approximation for a real gas?

tem 51

Solution

Mark The term "ideal gas" refers to a gas for which certain assumptions have been made. Which one of the following assumptions applies to an ideal gas? A
) The law PV = nRT2 is strictly obeyed. B
) Intermolecular forces are infinitely large. C
) Individual molecular volume and intermolecular forces are negligible.
It is assumed that the molecules in an ideal gas have no volume and that there are no interactions between the molecules. Thus, C is the best answer.


D
) One mole occupies a volume of 22.4 L at 25°C and 1 atm pressure.

I know that C is blatantly true..as per the definition of ideal gas law saying that individual molecular volume and IF's are completely negligible....but i thought STP was always true for any gas?

Technically wouldn't ether and ketone both be H-bond acceptors?

RE: Question 128...

If Can C=O hydrogen bond, but then why can't ethers? Don't they also have two lone pairs?

Thanks

 

[ThrusH]

43)Is it possible for a single particle passing through a multiwire proportional chamber to initiate more than one anode signal?

[/SIZE]A) No, because there would be only one ionization trail through the chamber
B) No, because only one electron cascade at a time is physically possible
C) Yes, if the applied voltage is sufficiently low
D) Yes, if the ionization trail is equidistant from more than one anode wire

This is a special case in which a charged particle (electron) can be equally detected by two anodes if the particle’s trail is equidistant between two adjacent anodes. There is no preference for one anode over another. Thus, D is the best answer.

46)The spatial resolution of stacked multiwire proportional chambers is determined by the:
A) applied voltage.
B) density of the ionizing gas.
C) density of particle tracks.
D) spacing of the anode wires.

Spatial resolution refers to the ability to locate an event in space. The closer the spacing of the anode wires, the better one can specify where an event took place—this is a limiting factor. Thus, D is the best answer.

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?

 

[afruff23]

Hi guys. Can somebody explain to me how D is correct for #24 on PS?:



What I don't understand is how you know that H2O2 is oxidized to O2, instead of H2O (this was what I presumed and therefore I got it wrong). To me, it seemed that H2O2 --> H2O + O-, and the highly unstable O- anions would come together to form O2. I don't know, does someone know what's going on here? Thanks!

I am in the same boat. I searched through this thread, and nobody explained why would you use the peroxide->oxygen part of the reaction for answering the question. How do you do this problem exactly in terms of knowing which parts of the reaction to focus on to answer the question?

 

[Handinhand]

Verbal crushed me on this one, a full 3-4 points below my average.

13,8,13 (49/52, 27/40, 49/52). I'm chalking it up as a fluke, and my hunger and the two dumb bitches behind me in the library talking didn't help anything.

What a curve though. 3 wrong on BS and PS for a 13? That's a little ridiculous. Made stupid mistakes, but can't get that worked up obviously. I'm just worried about Verbal. Did anybody else think it was abnormally hard?

 

[rls303]

Hi guys,
I'm confuses as to why A is not a viable answer and the answer is B. The reaction of the antibodies happens specifically at the site of the kidneys?

I did okay on this section, but I confess, I remembered a few answers from 3 months ago.

Thanks in advance!

 

[haylp]

I know that C is blatantly true..as per the definition of ideal gas law saying that individual molecular volume and IF's are completely negligible....but i thought STP was always true for any gas?

Technically wouldn't ether and ketone both be H-bond acceptors?

RE: Question 128...

If Can C=O hydrogen bond, but then why can't ethers? Don't they also have two lone pairs?

Thanks

Indeed. D would have been the choice had the temperature been 0 degrees Celcius or 273 K. Alas. C it is.

 

[phonyreal98]

Can someone explain to me what's going on in Passage 7 of PS? I actually ended up doing ok on the questions...but I still don't understand what's going on...

 

[IamSuperDoctor]

yep, assraped by verbal.

 

[emericana]

I saw someone else answered this earlier but I couldnt understand the explanation.

My questions:

I seriously do not understand the wording of the passage and was helping someone could explain it to me.

What side is the penny?
Is it Cu(NH3)4 2+?

If Cu(NH3)4 2+ is indeed the penny, how do you determine the oxidation state of Copper here?

So H is +1... so since there are 12 H that would make +12... and we need to get down to +2 .

How would we do this? Can someone explain this?

And then Cu 2+ on the right side would be +2?

Both the Kaplan and TPR book I have do not explain this adequately.

Just a few days before my exam so any help would be greatly greatly appreciated.

 

[appleicecream]

I took this yesterday and was confused with the same question. Somehow, I got it right. I was so confused with this compound, I turned to the copper compound in the equation below (equation 3 or 4?) and figured it out to be +2.
I used the process of elimination to get rid of any answer that did not end with +2. I read the explanation and it involved Cu(NH3)4 2+ and then got confused again.
Sorry I couldn't help much.. I just wanted to let you know that you weren't alone!

I saw someone else answered this earlier but I couldnt understand the explanation.

My questions:

I seriously do not understand the wording of the passage and was helping someone could explain it to me.

What side is the penny?
Is it Cu(NH3)4 2+?

If Cu(NH3)4 2+ is indeed the penny, how do you determine the oxidation state of Copper here?

So H is +1... so since there are 12 H that would make +12... and we need to get down to +2 .

How would we do this? Can someone explain this?

And then Cu 2+ on the right side would be +2?

Both the Kaplan and TPR book I have do not explain this adequately.

Just a few days before my exam so any help would be greatly greatly appreciated.