Test: Aromatic Electrophilic Substitution - NEET MCQ

The correct answer is Option B.
Fuming sulphuric acid, H₂S₂O₇, can be thought of as a solution of SO₃ in sulphuric acid - and so is a much richer source of the SO₃. Sulphur trioxide is an electrophile because it is a highly polar molecule with a fair amount of positive charge on the sulphur.

The correct answer is Option B.
Nitration is electrophilic substitution reaction; in its first step HNO3 takes protons from sulphuric acid and then forms −NO2+ so here HNO3 acts as base.
 
Mechanism of reaction as shown

The correct answer is option B

The correct answer is option D

Halonium ion act as electrophile in halogenation. Nitronium ion is used in nitration. Sulphonium ion is used in sulphonation. Acylium ion is used in acylation.

The correct answer is Option A
Toluene is having one methyl group which is an electron-donating group causing a negative charge on the carbon atom of the ring so it is highly reactive towards electrophile which is already electron deficient.
Benzene has a delocalised set of electron clouds which attracts electrophile while chloro and nitro group are electronegative causing positive charge on carbon atoms so are not reactive towards electrophilic substitution.
Cl shows -I effect and −NO₂ shows a strong electron-withdrawing effect. So least reactive
a)IV < III < II < I
 

Understanding the Compound

- The compound C6H4Br2(P) is a dibromo benzene. This means it has two bromine atoms attached to the benzene ring.

Understanding Isomerism

- The less polar isomer refers to the geometric arrangement of the bromine atoms on the benzene ring that results in less polarity.
- In the case of dibromo benzene, there are three possible geometric arrangements (ortho, meta, and para) but only ortho-dibromo benzene and para-dibromo benzene are polar. The less polar of the two is the para isomer.

Nitration Reaction

- Nitration is a general class of a chemical process for the introduction of a nitro group into an organic chemical compound.
- The nitration of benzene involves substitution of a hydrogen atom by a nitro group (-NO2) and this is facilitated by a mixture of concentrated nitric acid (HNO3) and sulfuric acid (H2SO4).

Mono Nitration Products

- Considering that the compound is para-dibromo benzene, the nitration can occur at any of the 4 remaining carbon atoms in the benzene ring.
- However, since the question asks for mono nitration products (meaning only one nitro group is added), the number of unique products will depend on the symmetry of the molecule.
- For para-dibromo benzene, the molecule is symmetric. Nitration at any of the 4 remaining positions will result in only 2 unique mono-nitration products due to this symmetry.

So, the answer is 2.

C7H8 is toluene: that’s the only benzenoid isomer possible. To get C7H8O, you must mentally “insert an oxygen atom” somewhere.
There are 5 ways you can mentally insert an oxygen atom into a C-C or C-H bond of toluene.
So the isomers of C7H8O are:
2-methylphenol = o-cresol
3-methylphenol = m-cresol
4-methylphenol = p-cresol
benzyl alcohol = phenylmethanol = (hydroxymethyl)benzene
methoxybenzene = anisole = methyl phenyl ether

The correct answer is: