Explore topic-wise MCQs in Organic Chemistry.

This section includes 17 Mcqs, each offering curated multiple-choice questions to sharpen your Organic Chemistry knowledge and support exam preparation. Choose a topic below to get started.

1.

What is the specific optical rotation of (S)-malic acid at a concentration of 5.5 g/ mL in the solvent pyridine at 20°C at a wavelength of 589 nm?

A. the specific rotation is –27°
B. the specific rotation is +27°
C. the specific rotation is –17°
D. the specific rotation is +17°
Answer» B. the specific rotation is +27°
Discussion
2.

Which of these is a comparatively insignificant factor affecting the magnitude of specific optical rotation?

A. Concentration of the substance of interest
B. Purity of the sample
C. Temperature of the measurement
D. Length of the sample tube
Answer» D. Length of the sample tube
Discussion
3.

What can be said with certainty if a compound has α= -9.25°?

A. The compound has the (S) configuration
B. The compound has the (R) configuration
C. The compound is not a meso form
D. The compound possesses only one stereogenic center
Answer» D. The compound possesses only one stereogenic center
Discussion
4.

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)
Answer» C. 50%(R) 50%(S)
Discussion
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°
Answer» C. +15°
Discussion
6.

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
Answer» B. α gets halved
Discussion
7.

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°
Answer» E.
Discussion
8.

WHICH_OF_THESE_IS_A_COMPARATIVELY_INSIGNIFICANT_FACTOR_AFFECTING_THE_MAGNITUDE_OF_SPECIFIC_OPTICAL_ROTATION??$

A. Concentration of the substance of interest
B. Purity of the sample
C. Temperature of the measurement
D. Length of the sample tube
Answer» D. Length of the sample tube
Discussion
9.

What_is_the_specific_optical_rotation_of_(S)-malic_acid_at_a_concentration_of_5.5_g/_mL_in_the_solvent_pyridine_at_20°C_at_a_wavelength_of_589_nm?$#

A. the specific rotation is –27°
B. the specific rotation is +27°
C. the specific rotation is –17°
D. the specific rotation is +17°
Answer» B. the specific rotation is +27¬¨¬®‚Äö√†√ª
Discussion
10.

What can be said with certainty if a compound has α= -9.25°?#

A. The compound has the (S) configuration
B. The compound has the (R) configuration
C. The compound is not a meso form
D. The compound possesses only one stereogenic center
Answer» D. The compound possesses only one stereogenic center
Discussion
11.

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)
Answer» C. 50%(R) 50%(S)
Discussion
12.

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

A. CH<sub>3</sub>
B. CH<sub>2</sub>Cl
C. CH<sub>2</sub>OH
D. CHO
Answer» C. CH<sub>2</sub>OH
Discussion
13.

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°
Answer» C. +15¬¨¬®‚Äö√†√ª
Discussion
14.

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
Answer» B. ‚âà√≠¬¨¬± gets halved
Discussion
15.

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
Answer» B. change of the electrical conductivity of solution with composition
Discussion
16.

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°
Answer» E.
Discussion
17.

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» C. Concentration of the substance
Discussion