Test Prep Test Prep Certifications OAT Questions & Answers

• Question 21:

  Which of the following, when reacted with benzene, will direct an ortho/para configuration?

  A. -COOH

  B. -Cl

  C. -CH3

  D. NO2

  E. 2 of the above

  Correct Answer: E

  Halogens, such as Cl− and R groups, such as CH3, both direct benzene in an ortho/para configuration. The other answer choices direct in a meta configuration. Know ortho/para/meta along with activating and deactivating groups from the heart!

• Question 22:

  Which of the following is false regarding SN2 reactions?

  A. SN2 occurs in one step.

  B. Common solvents include DMSO and acetone.

  C. Steric hindrance increases from primary to secondary to tertiary.

  D. SN2 prefers to proceed with strong nucleophiles.

  E. None of the above.

  Correct Answer: E

  All of the answer choices accurately represent SN2 reactions.

• Question 23:

  What is the relationship between the following two molecules?

  

  A. Enantiomers

  B. Identical compounds

  C. Meso compounds

  D. Diastereomers

  E. Structural isomers

  Correct Answer: D

  Due to the molecules not being mirror images of each other and non-superimposable, they are indeed diastereomers.

• Question 24:

  Identify the missing reagent in the reaction below:

  

  A. 1) BH3, THF; 2) H2O2, OH

  B. CH2N2, Heat

  C. Cl2, CCl4

  D. 1) OsO4; 2) NaHSO3

  E. 1) O3; 2) Zn, H2O

  Correct Answer: C

• Question 25:

  Which of the following compounds is the weakest acid?

  

  A. Option A

  B. Option B

  C. Option C

  D. Option D

  E. Option E

  Correct Answer: B

  Understanding how to solve these type of problems where a benzene has various substituents that alter its pH depends on understanding electron-withdrawing substituents (fluorine and chlorine) and electron-donating substituents (hydroxyl and methyl, with the former being more powerful). The electron-donating substituents destabilize the nitrogen's lone pair of electrons, thus increasing its reactivity and making it more basic (less acidic).

• Question 26:

  Identify the starting molecule in this reaction: A. Option A

  

  B. Option B

  C. Option C

  D. Option D

  E. Option E

  Correct Answer: C

• Question 27:

  In IUPAC nomenclature, which of the following functional groups has the highest priority in numbering a parent chain?

  A. Alkanes

  B. Alkenes

  C. Alkynes

  D. Amines

  E. Esters

  Correct Answer: E

• Question 28:

  Which of the following has the higher acidity?

  

  A. Option A

  B. Option B

  C. Option C

  D. Option D

  E. Option E

  Correct Answer: C

  In phenols, the closer the substituent is to the OH, the stronger the acid (O > M > P). Same applies to electronegative: the more electronegative the halogen is, the stronger the acid (ex. F > Cl > Br). Thus, C is the more electronegative and closer substituent to the OH, making it the more acidic ph.

• Question 29:

  What is the percent composition of potassium in potassium dichromate?

  A. 26.5%

  B. 35.4%

  C. 33.3%

  D. 38.1%

  E. Cannot be determined.

  Correct Answer: A

  The molecular formula of potassium dichromate is K2Cr2O7. To find the percent composition, calculate

  the weight of the entire molecule:

  (2 × 39 g/mol) + (2 × 52 g/mol) + (7 × 16 g/mol) = 294 g/mol

  Then divide the weight of the potassium in the molecule by the entire molecular weight:

  (2 × 39 g/mol) / 294 g/mol = 0.265

  Multiply ×100 to produce the percentage value: 0.265 × 100 = 26.5%

• Question 30:

  A vessel contains 0.50 moles of nitrogen, 0.40 moles of carbon and 0.10 moles of chlorine at a total pressure of 4.0 atm. What is the partial pressure of the chlorine?

  A. 0.40 atm

  B. 2.00 atm

  C. 1.60 atm

  D. 1.00 atm

  E. Cannot be calculated with this information.

  Correct Answer: A

  Begin by calculating the mole fraction of the chlorine: Moles of Cl / Total Moles –andgt; 0.10 mol Cl / 1.0 mol = 0.10 Then multiply the fraction by the total pressure of the system: 0.10 × 4 atm = 0.4 atm