MolSynapsequestion bank

MolSynapse / Question bank / Structural Identification and Practical Organic Chemistry / Degree of unsaturation and spectroscopic clues

JEE Advanced levelSingle correct optionDifficulty 3 of 3si098

Naphthalene, $C X_{10} H X_{8}$ , is completely hydrogenated to decalin, $C X_{10} H X_{18}$ (bicyclic and saturated). The number of moles of $H X_{2}$ used per mole of naphthalene is

A3
B4
C7
D5

Answer: D

Naphthalene has degree of unsaturation

(22 - 8) /2 = 7

and decalin has

(22 - 18) /2 = 2

(two rings). The 5 pi bond equivalents lost correspond to 5 mol of

H X_{2}

; check:

C X_{10} H X_{8} + 5 H X_{2} C X_{10} H X_{18}

.

Practice Structural Identification and Practical Organic Chemistry More on Degree of unsaturation and spectroscopic clues

Previous questionNext question

More questions on Degree of unsaturation and spectroscopic clues

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 onl... JEE Advanced level
Which of the following have a degree of unsaturation equal to 5? JEE Advanced level