Solved Examples - General Organic Chemistry Notes | Study Mock Test Series for JEE Main & Advanced 2022 - JEE

Q.1. Arrange the following compounds in order of decreasing acidity:  (IIT- JEE 2013)
(a) I  > II > III > IV
(b) III > I > II > IV
(c) IV > III > I > II
(d) II > IV > I > III

Correct Answer is Option (b)

• Electron donating groups increase the acidity of phenol when present as a substituent on the benzene ring while electron-withdrawing groups decrease the acidity of phenol.
• Cl and NO₂ are electron-withdrawing groups while -CH₃ and -OCH₃ are electron donating groups.
• However, nitro undergoes resonance, which allows it to better stabilize the negative charge of the oxygen compared to chlorine. Thus, acidic character of nitrophenol would be higher than that of chlorophenol.
• So, Nitrophenol is the most acidic compound here followed by chlorophenol.
  Hence, the correct option is b.

Q.2. Which of the given statement(s) about N, O, P and Q with respect to M is (are) correct?    (IIT-JEE 2012)
(a) M and N are non–mirror image stereoisomers.
(b) M and O are identical.
(c) M and P are enantiomers.
(d) M and Q are identical.

Correct Answer is Option (a), (b) & (c)
Fischer Projections of the molecules:

It is clear that:

• M and N are non-mirror image stereoisomers.
• M and O are the same molecules i.e. Identical.
• M and P are the non-superimposable mirror images of hence they are enantiomers.
• N and Q are identical.
• M and Q are also are non–mirror image stereoisomers i.e diastereomers.
  Hence A, B and C are the correct statements.

Q.3. The total number of cyclic isomers possible for a hydrocarbon with the molecular formula C₄H₆ is ____   (IIT-JEE 2010)

5 cyclic isomers are possible for C₄H₆, possible.