Study for the chemistry section of the DAT exam's Survey of Natural Sciences. Try these practice questions in general and organic chemistry to prepare for the DAT (Dental Admission Test).
1. Which of the following compounds has the greatest percent hydrogen by mass?
A. HF
B. HCl
C. HBr
D. HAt
E. HI
(A) The molar mass is smallest for HF. Hydrogen contributes more to the molar mass than in the other formulas.
2. Which of the following molecules has a molar mass of 78 grams?
A. H2
B. C2H2
C. SO3
D. CH2Cl2
E. C6H6
(E) Add the atomic masses for all atoms in the formula. MM = 6 × 12.0 + 6 × 1.0 = 78.
3. Which of the following reactions requires the least energy?
A. dissociation of O2 molecules
B. dissociation of F2 molecules
C. dissociation of Cl2 molecules
D. dissociation of Br2 molecules
E. dissociation of N2 molecules
(B) Fluorine is the most reactive of the Group 7A elements. This reactivity is partly due to the weakest single bond.
4. Which of the following types of radiation is the most dangerous?
A. beta
B. gamma
C. alpha
D. neutrons
E. ultraviolet
(B) Gamma radiation has the highest energy and is the most penetrating. Beta particles can be stopped by a sheet of aluminum. Alpha radiation can be stopped by a layer of paper.
5. Which of the following salts will form a neutral aqueous solution?
A. NaF
B. NaCN
C. NaHSO3
D. NaCl
E. NaOH
(D) Sodium chloride is the salt formed by the reaction of a strong acid and a strong base. This type of salt forms a neutral solution.
6. Of the following free radicals, which will be the most stable?
A. methyl carbon
B. primary carbon
C. tertiary carbon
D. secondary carbon
E. hydrogen atom
(C) The more carbons and branched the free radical, the more stable the free radical will be. Radicals that have resonance possibilities are more stable.
7. What type of isomer will rotate plane polarized light?
A. Enantiomer
B. Diastereomer
C. Constitutional
D. Hydration
E. Cis-trans
(A) Enantimers are mirror images of one another.
8. Which of the following has a skeleton of eight carbon atoms?
A. pentane
B. butane
C. hexane
D. heptane
E. octane
(E) An octane has eight carbon atoms in the longest chain.
9. Which of the following would not make a good leaving group?
A. iodide
B. hydroxide
C. halides
D. chloride
E. methyl
(E) A good leaving group would be stable in an ionic form in water; methyl does not form a stable cation or anion.
10. A Claisen Rearrangement will produce which of the following types of compounds?
A. amine derivative
B. phenol derivative
C. carboxylic acid derivative
D. alkyne derivative
E. halide derivatives
(B) The Claisen Rearrangement tends to cause phenyl-ethers to internally rearrange to form o-substituted phenols.