ADA Practice Test - Chem/Orgo

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If the mass of oxygen in a nitrogen-oxygen compound is known, given the mass percent of oxygen, all of the following are needed to determine the molecular formula of a nitrogen-oxygen compound EXCEPT one. Which one is this EXCEPTION?
A. Atomic mass of nitrogen
B. Atomic mass of oxygen
C. Avogadro's number
D. Empirical formula
E. Molar mass of the compound

Which of the following statements is true regarding a pair of compounds that are diasteromers of each other?
A. They are configurational isomers.
B. They have the same physical
properties.
C. They are mirror images.
D. They are always optically active.
E. They have equal but oppisite α values.

A person eats a muffin containing 14C-labeled carbohydrate. Following digestion where is the first place high levels of radioactivity would accumulate is the
A. Heart.
B. Spleen.
C. Pancreas.
D. Liver.
E. Colon.

for this question i narrowed it down to liver or colon since the veins in teh colon would be where the glucose is... but maybe i read too much into it?

Also there are 2 orgo question in the ATTACHMENTS! THX!!!!!!

 

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any1?

 

[aqz]

In order:

C, A, D, B. Not sure about the 2nd orgo question, but it seems like it has to be B.

Avogadro's number is only used to convert moles to molecules, you don't need it for % mass.

Configurational isomers = stereoisomers.

Liver ALWAYS gets first dibs on food after it's processed into small intestine.

NO2 withdraws electons (meta directing) while CH3 donates electrons (ortho/para). However NO2 has a far stronger effect than CH3, so one Br will add meta to the ring.

I think it can only be B because I don't know how CN could possibly form CH3 without anything to reduce CN. Asides from B where you have an electrophilic attack to the carbonyl and then you could add a CH3 on there somehow then have an acidic workup to form the OH, none of the other choices seem probable.....they're all either substitution reactions or have bad leaving groups.

 

[412smb412]

In order:

C, A, E, B. Not sure about the 2nd orgo question, but it seems like it has to be B.

Avogadro's number is only used to convert moles to molecules, you don't need it for % mass.

Configurational isomers = stereoisomers.

Liver ALWAYS gets first dibs on food after it's processed into small intestine.

NO2 withdraws electons (meta directing) while CH3 donates electrons (ortho/para). However NO2 has a far stronger effect than CH3, so one Br will add meta to the ring.

I think it can only be B because I don't know how CN could possibly form CH3 without anything to reduce CN. Asides from B where you have an electrophilic attack to the carbonyl and then you could add a CH3 on there somehow then have an acidic workup to form the OH, none of the other choices seem probable.....they're all either substitution reactions or have bad leaving groups.

answers were: D, A, D, E. i guess there's a mistake for the avagadros. but why did u say configurational isomers as supposed to b. ? isn't configuration the orientation in space?

also for the digestion question... i understand the pathway of metabolism and what not but the wording led me to believe it would be intestine b4 the liver? i dunno... is the real dat's wording like this?

 

[aqz]

My bad, I meant D for the 3rd question. "Liver gets first dibs"

For the 1st orgo question....I've never seen Br2/FeBr3 add onto a ring twice, and this doesn't say excess Br2. Should still be the 1 Br added on meta.

Like I said, configurational isomer = stereoisomer. Wikipedia it. Also, ENANTIOMERS not diastereomers have the same physical properties.

 

[412smb412]

My bad, I meant D for the 3rd question. "Liver gets first dibs"

For the 1st orgo question....I've never seen Br2/FeBr3 add onto a ring twice, and this doesn't say excess Br2. Should still be the 1 Br added on meta.

Like I said, configurational isomer = stereoisomer. Wikipedia it. Also, ENANTIOMERS not diastereomers have the same physical properties.

ohhh I see! thanks! also is the wording on the dat like this?

could u take a look at the practice OAT and tell me how it compares? thx!

https://www.ada.org/oat/oat_sample_test.pdf

 

[aqz]

If I didn't know that was the OAT, I would've thought it was just another practice DAT.

Very similar.