Explore topic-wise MCQs in Organic Chemistry.

This section includes 15 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.

The ultraviolet spectrum of benzonitrile shows a secondary absorption band at 271 nm. If a solution of benzonitrile in water, with a concentration of 1×10-4 molar solution is examined at 271 nm, what will be the absorbance reading (ℇ = 1000) and what will be the intensity ratio, IO/I, respectively?

A. 0.1, 1.26
B. 0.2, 2.26
C. 0.3, 3.26
D. 0.4, 4.26
Answer» B. 0.2, 2.26
2.

The ultraviolet spectrum of benzonitrile shows a primary absorption band at 224 nm. If a solution of benzonitrile in water, with a concentration of 1x 10-4 molar, is examined at a wavelength of 224 nm, the absorbance is determined to be 1.30. The cell length is 1 cm. What is the molar absorptivity of this absorption band?

A. 2.3 x 104
B. 3.3 x 104
C. 1.3 x 104
D. 4.3 x 104
Answer» D. 4.3 x 104
3.

Which of the following is the correct order of λmax for n–> π* transition for the given compounds?

A. 1>2>3>4>5
B. 1<2<3<4<5
C. 1>2<3>4<5
D. 1>2>3<4>5
Answer» B. 1<2<3<4<5
4.

What is the correct order of λmax for n–> π* transition for the following three compounds?

A. RCOOH > RCOOR’ > RCONH2
B. RCOOH = RCOOR’ = RCONH2
C. RCOOH = RCOOR’ < RCONH2
D. RCOOH = RCOOR’ > RCONH2
Answer» C. RCOOH = RCOOR’ < RCONH2
5.

What is the correct order of λmax for π –> π* transition for the following three compounds?

A. R-C=C-R > R2C = CR2 > R-CHO
B. R-C=C-R < R2C = CR2 < R-CHO
C. R-C=C-R = R2C = CR2 = R-CHO
D. R-C=C-R < R2C = CR2 >R-CHO
Answer» C. R-C=C-R = R2C = CR2 = R-CHO
6.

What is the correct order of λmax for n –> π* transition for the R-CN, R-NO2, and R-N=N-R?

A. R-CN < R-NO2 < R-N=N-R
B. R-CN = R-NO2 = R-N=N-R
C. R-CN > R-NO2 > R-N=N-R
D. R-CN > R-NO2 < R-N=N-R
Answer» B. R-CN = R-NO2 = R-N=N-R
7.

What is the correct order of λmax for n –> σ* transition?

A. R-OH > R-NH2 > R-SH
B. R-OH < R-NH2 < R-SH
C. R-OH > R-SH > R-NH2
D. R-OH < R-SH < R-NH2
Answer» C. R-OH > R-SH > R-NH2
8.

Which of the following comparison is correct for solvent shift on the n –>π* transition of acetone?

A. H20 = CH30H = C2H50H = CHC13 = C6H14
B. H20 > CH30H > C2H50H > CHC13 > C6H14
C. H20 < CH30H < C2H50H < CHC13 < C6H14
D. H20 > CH30H < C2H50H < CHC13 < C6H14
Answer» D. H20 > CH30H < C2H50H < CHC13 < C6H14
9.

THE_ULTRAVIOLET_SPECTRUM_OF_BENZONITRILE_SHOWS_A_SECONDARY_ABSORPTION_BAND_AT_271_NM._IF_A_SOLUTION_OF_BENZONITRILE_IN_WATER,_WITH_A_CONCENTRATION_OF_1‚ÄÖ√†√∂‚Àւ•10-4_MOLAR_SOLUTION_IS_EXAMINED_AT_271_NM,_WHAT_WILL_BE_THE_ABSORBANCE_READING_(‚ÄÖ√Ñ√∂‚ÀÖ√´‚ÀÖ¬∞_=_1000)_AND_WHAT_WILL_BE_THE_INTENSITY_RATIO,_IO/I,_RESPECTIVELY??$#

A. 0.1, 1.26
B. 0.2, 2.26
C. 0.3, 3.26
D. 0.4, 4.26
Answer» B. 0.2, 2.26
10.

The ultraviolet spectrum of benzonitrile shows a primary absorption band at 224 nm. If a solution of benzonitrile in water, with a concentration of 1x 10-4 molar, is examined at a wavelength of 224 nm, the absorbance is determined to be 1.30. The cell length is 1 cm?

A.
B. 2.3 x 10<sup>4</sup>
C. 3.3 x 10<sup>4</sup>
Answer» D.
11.

What is the correct order of λmax for π –> π* transition for the following three compounds?$

A. R-C<span style="text-decoration:overline;">=</span>C-R > R<sub>2</sub>C = CR<sub>2</sub> > R-CHO
B. R-C<span style="text-decoration:overline;">=</span>C-R < R<sub>2</sub>C = CR<sub>2</sub> < R-CHO
C. R-C<span style="text-decoration:overline;">=</span>C-R = R<sub>2</sub>C = CR<sub>2</sub> = R-CHO
D. R-C<span style="text-decoration:overline;">=</span>C-R < R<sub>2</sub>C = CR<sub>2</sub> >R-CHO
Answer» C. R-C<span style="text-decoration:overline;">=</span>C-R = R<sub>2</sub>C = CR<sub>2</sub> = R-CHO
12.

What is the correct order of λmax for n –> π* transition for the R-CN, R-NO2, and R-N=N-R?$

A. R-CN < R-NO<sub>2</sub> < R-N=N-R
B. R-CN = R-NO<sub>2</sub> = R-N=N-R
C. R-CN > R-NO<sub>2</sub> > R-N=N-R
D. R-CN > R-NO<sub>2</sub> < R-N=N-R
Answer» B. R-CN = R-NO<sub>2</sub> = R-N=N-R
13.

What is the correct order of λmax for n –> σ* transition?$

A. R-OH > R-NH<sub>2</sub> > R-SH
B. R-OH < R-NH<sub>2</sub> < R-SH
C. R-OH > R-SH > R-NH<sub>2</sub>
D. R-OH < R-SH < R-NH<sub>2</sub>
Answer» C. R-OH > R-SH > R-NH<sub>2</sub>
14.

Which of the following comparison is correct for solvent shift on the n –>π* transition of acetone?$

A. H<sub>2</sub>0 = CH<sub>3</sub>0H = C<sub>2</sub>H<sub>5</sub>0H = CHC1<sub>3</sub> = C<sub>6</sub>H<sub>14</sub>
B. H<sub>2</sub>0 > CH<sub>3</sub>0H > C<sub>2</sub>H<sub>5</sub>0H > CHC1<sub>3</sub> > C<sub>6</sub>H<sub>14</sub>
C. H<sub>2</sub>0 < CH<sub>3</sub>0H < C<sub>2</sub>H<sub>5</sub>0H < CHC1<sub>3</sub> < C<sub>6</sub>H<sub>14</sub>
D. H<sub>2</sub>0 > CH<sub>3</sub>0H < C<sub>2</sub>H<sub>5</sub>0H < CHC1<sub>3</sub> < C<sub>6</sub>H<sub>14</sub>
Answer» D. H<sub>2</sub>0 > CH<sub>3</sub>0H < C<sub>2</sub>H<sub>5</sub>0H < CHC1<sub>3</sub> < C<sub>6</sub>H<sub>14</sub>
15.

What is the wavelength range for UV spectrum of light?

A. 400 nm – 700 nm
B. 700 nm to 1 mm
C. 0.01 nm to 10 nm
D. 10 nm to 400 nm
Answer» E.