some ?'s from my practice DAT today

[vixen]

1) what's a planaria? It was mentioned in a question.

2) also, lacteals absorb:
A) carb's
B) proteins
C) fatty acids
D) salts
E)water

answer is C. I put A...wasnt sure why.

3) which selection most likely leads to speciation?
A) directional selection
B) disruptive selection
C) sexual selection
D) stabilizing selection

answer is B....I thought it was B, what is "disruptive selection"?

4) when empty, the mass of a beaker is 115g. when filled w/300mL of an unknown liquid, the combined mass is 427g. what volume (in mL) would 1kg of the liquid occupy?

A) (300)(1000)/(427-115)
B) (300)(1000)(427-115)
C) 300/427
D) 300/(427-115)

answer is A....dont why youd multiply by 1000 first...

5) which of the following is not a good conductor of electricity?
A) Fe (s)
B) NaCl (aq)
C) NaCl (l)
D) NaCl (s)
E) Cu (s)

Answer is D. I dont know why

6) Which of the following compounds is not capable of hydrogen bonding?
A) C4H11N
B) C4H9NO
C) C4H7F3
D) C4H8O2
E) C4H10O

answer is C. I remembered that FON can hydrogen bond, so why can't C?

7) Which of the following cmps may be classified as a protic solvent?
A) diethyl ether
B) n-hexane
C) acetone
D) ethanol
E) nitrobenzene

answer is D. is this just knowing which things are protic and which aren't....i can't remember for my life.

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[DesiDentist]

Originally posted by vixen
1) what's a planaria? It was mentioned in a question.

]I believe planaria is a type of flat worm (Platyhelminthes). I'm not sure though.

2) also, lacteals absorb:
A) carb's
B) proteins
C) fatty acids
D) salts
E)water

answer is C. I put A...wasnt sure why.

Lacteals absorb Fatty Acids in the Duodenum, the first part of the small intestine. They take the fatty acids to the lymphatic system, unlike the villi that take digested carbs and proteins straight to the blood stream.

3) which selection most likely leads to speciation?
A) directional selection
B) disruptive selection
C) sexual selection
D) stabilizing selection

answer is B....I thought it was B, what is "disruptive selection"?
If you thought the answer was B you are right !!Read the Natural Selection part of the Kaplan book. You should know these, even though it is a rare question.



4) when empty, the mass of a beaker is 115g. when filled w/300mL of an unknown liquid, the combined mass is 427g. what volume (in mL) would 1kg of the liquid occupy?

A) (300)(1000)/(427-115)
B) (300)(1000)(427-115)
C) 300/427
D) 300/(427-115)

answer is A....dont why youd multiply by 1000 first...

My brain is too fried to figure this one out.

5) which of the following is not a good conductor of electricity?
A) Fe (s)
B) NaCl (aq)
C) NaCl (l)
D) NaCl (s)
E) Cu (s)

Answer is D. I dont know why

Remember that a good conductor is a solid metal or a ionic liquid. Fe and Cu are solids and are transition metals thus making them fit their stereotype of good conductors. NaCl is table salt and in a liquid (aq) or (l) it conducts energy since the medium contains cations (Na+) and Anions (Cl-). Solid NaCl will not dissociate without being in liquid

6) Which of the following compounds is not capable of hydrogen bonding?
A) C4H11N
B) C4H9NO
C) C4H7F3
D) C4H8O2
E) C4H10O

answer is C. I remembered that FON can hydrogen bond, so why can't C?


This has to do with inductive effects. Since there are 3 Flourines, the most electronegative element it refuses to let H-bonding take place with ease.

7) Which of the following cmps may be classified as a protic solvent?
A) diethyl ether
B) n-hexane
C) acetone
D) ethanol
E) nitrobenzene

answer is D. is this just knowing which things are protic and which aren't....i can't remember for my life.


anything with an -OH is a protic solvent.

Hope this helps. How did you do otherwise on the practice exam?

DesiDentist

 

[vixen]

yeah! thanks desi!!!

 

[Dentalstu02]

For #4,
Think of it as a ratio, 300ml per (427-115)g. Or 300ml/312g. This value gives the milliliters per gram (look at the units). SO for 1000 grams (1 kilogram) we just multiply by 1000g. SO we get (1000)(300)/(312)
I hope this makes sense...

 

[DesiDentist]

Seema,

I just got it. Planaria is a flat worm.

DesiDentist

 

[vixen]

thanks guys.