Degree of unsaturation and spectroscopic clues

28 questions on Degree of unsaturation and spectroscopic clues from the Structural Identification and Practical Organic Chemistry chapter: 6 NEET level, 11 JEE Main, 11 JEE Advanced. Each one opens with its answer and solution.

• The degree of unsaturation of benzene, C6H6, is NEET level
• A strong, sharp infrared absorption near 1715 cm^-1 in the spectrum of an organic compound indicates the presence of NEET level
• The number of signals in the ^1H NMR spectrum of dimethyl ether, CH3OCH3, is NEET level
• According to the nitrogen rule, an organic compound containing only C, H, O and one nitrogen atom has a molecular ion peak at an m/z value that is NEET level
• The degree of unsaturation of C3H5Cl is NEET level
• Which of the following compounds shows a broad infrared absorption band centred near 3300 cm^-1 and no strong band in the 1700-1750 cm^-1 region? NEET level
• The degree of unsaturation of C7H7NO2 is JEE Main level
• Calculate the degree of unsaturation of C9H10ClNO3 (give the nearest integer). JEE Main level
• A compound C6H10 takes up only one mole of H2 per mole over Pd/C under mild conditions (rings are not opened) to give C6H12. The compound contains JEE Main level
• The number of signals in the ^1H NMR spectrum of 1,4-dimethylbenzene (p-xylene) is JEE Main level
• The number of signals in the ^13C NMR spectrum of 1,3,5-trimethylbenzene is JEE Main level
• Which compound shows a medium, sharp infrared band near 2250 cm^-1? JEE Main level
• In the mass spectrum of 1,2-dibromoethane, BrCH2CH2Br, the molecular ion cluster M : M+2 : M+4 has intensities in the approximate ratio JEE Main level
• Which of the following has a molecular ion at an odd m/z value (use ^12C, ^1H, ^14N, ^16O)? JEE Main level
• Assertion (A): The O-H stretching band of a carboxylic acid is broader than that of a dilute alcohol solution. Reason (R): Carboxylic acids exist as hydrogen-bo... JEE Main level
• A hydrocarbon C5H8 absorbs 2 mol of H2 over Pt to give pentane (CH3CH2CH2CH2CH3). Which of the following could it be? JEE Main level
• Which of the following compounds have a degree of unsaturation equal to 4? JEE Main level
• In a Kjeldahl determination, 0.620 g of an organic compound was digested and the ammonia evolved was neutralised exactly by 27.5 mL of 0.100 M H2SO4. Calculate ... JEE Advanced level
• A compound shows molecular ion peaks at m/z 112 and 114 with intensity ratio about 3:1 and contains 64.0% C, 4.4% H and 31.6% Cl by mass (C 12, H 1, Cl 35.5). I... JEE Advanced level
• Using ^12C, ^1H, ^14N, ^16O, which compounds show a molecular ion at an odd m/z value? JEE Advanced level
• A hydrocarbon C10H16 absorbs 2 mol of H2 over Pt to give C10H20, which absorbs no more H2. The number of rings and the number of pi bonds in the original hydroc... JEE Advanced level
• An alkene C6H12 gives only propanone on ozonolysis followed by Zn/H2O. The number of signals in the ^13C NMR spectrum of this alkene is JEE Advanced level
• Arrange in increasing order of lambda_max in UV-visible spectra: (i) ethene, (ii) buta-1,3-diene, (iii) hexa-2,4-diene (CH3CH=CH-CH=CHCH3), (iv) hexa-1,3,5-trie... JEE Advanced level
• Which of the following pairs of compound and characteristic infrared absorption are correctly matched? JEE Advanced level
• Which of the following show exactly two signals in the ^1H NMR spectrum (count each set of chemically equivalent hydrogens)? JEE Advanced level
• A compound shows molecular ion peaks at m/z 186, 188 and 190 in the ratio about 1:2:1 (lowest mass peak is from ^79Br only). It contains only C, H and Br, is sa... JEE Advanced level
• Naphthalene, C10H8, is completely hydrogenated to decalin, C10H18 (bicyclic and saturated). The number of moles of H2 used per mole of naphthalene is JEE Advanced level
• Which of the following have a degree of unsaturation equal to 5? JEE Advanced level