Gaokao Exam Chemistry: Organic Chemistry Fundamentals 2

Question 1

Which of the following is the correct IUPAC name for CH₃-CH(OH)-CH₂CH₃?

Accepted Answer

2-butanol

Answer

The longest chain has 4 carbons (butane). The -OH group is on carbon 2, making it 2-butanol.

Question 2

Benzene reacts with bromine in the presence of FeBr₃ catalyst. What type of reaction occurs?

Accepted Answer

Electrophilic substitution

Answer

Benzene undergoes electrophilic aromatic substitution (EAS) with Br₂/FeBr₃. FeBr₃ activates Br₂ to form the electrophile Br⁺.

Question 3

What is the degree of unsaturation (DBE) of the molecular formula C₆H₆?

Accepted Answer

4

Answer

DBE = (2×6 + 2 - 6)/2 = (12 + 2 - 6)/2 = 8/2 = 4. Benzene has 3 double bonds + 1 ring = 4 DBE.

Question 4

Ethanol undergoes oxidation with acidified potassium dichromate (K₂Cr₂O₇/H₂SO₄). What is the primary product under controlled conditions?

Accepted Answer

Ethanal (acetaldehyde)

Answer

Under controlled (mild) oxidation of a primary alcohol, the first product is an aldehyde (ethanal). Further oxidation gives the carboxylic acid.

Question 5

Which functional group is present in an ester?

Accepted Answer

-COO-

Answer

Esters contain the -COO- (ester linkage) functional group, formed from a carboxylic acid and an alcohol by condensation.

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