Organic Chemistry Multiple Choice Questions and Answers

1 What does a polarimeter measure?

A Polarity of the substance

B Angle of rotation of an optical active compound

C Concentration of the substance

D pH of the substance

Answer:Angle of rotation of an optical active compound

2 A solution of 0.1 g/mL of a pure R enantiomer in a 1.0 dm (i.e., 10 cm) polarimeter rotates plane polarized light by +4.8°. What is the rotation observed on this solution in a 2 dm polarimeter?

A +2.4°

B +4.8°

C +19°

D +9.6°

View Answer

Answer:+9.6°

3 Polarimeter works on the principle of which of the following?

A polarisation of light

B change of the electrical conductivity of solution with composition

C change of angle of refraction with composition

D change of electrical conductivity of solution with temperature

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Answer:polarisation of light

4 What is the effect of the I on the specific optical rotation (α), if I gets double?

A α gets double

B α gets halved

C α gets four times

D α eight times

View Answer

Answer:α gets double

5 If a solution of a compound (30.0 g/100 mL of solution) has a measured rotation of +15° in a 2 dm tube, what is the specific rotation?

A +50°

B +25°

C +15°

D +7.5°

View Answer

Answer:+25°

6 Which of the following groups has the highest priority according to the Cahn-Ingold-Prelog sequence rules?

A CH₃

B CH₂Cl

C CH₂OH

D CHO

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Answer:CH₂Cl

7 What is the percent composition of a mixture of (S)-(+)-2-butanol, α= +13.52°, and (R)-(-)-2-butanol, α = -13.52°, with a specific rotation α = +6.76°?

A 75%(R) 25%(S)

B 25%(R) 75%(S)

C 50%(R) 50%(S)

D 67%(R) 33%(S)

View Answer