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38
Subjective

Which of the following compounds are aromatic according to Huckel's rule?

Explanation

A. The compound has $8 \pi$ electrons. It will be non-aromatic. Both rings are non-benzenoid.

B. The compound is aromatic. It has $6 \pi e^{-}$delocalised electron $\left(4 \pi e^{-}+2\right.$ lone pair electrons), all the four carbon atoms and the N atom are $s p^2$ hybridised.

C. The compound contains $6 \pi$ electrons but not in the ring hence it is non-aromatic.

D. $10 \pi e^{-}$obeying Huckel rule and the ring is planar. It is aromatic.

E. In this compound one six membered planar ring has $6 \pi e^{-}$although it has $8 \pi$ electrons in two rings. It is therefore aromatic.

F. It has $14 \pi$ electrons in conjugation and in the planar ring, Huckel rule is verified. It will be aromatic.

39
Subjective

Suggest a route to prepare ethyl hydrogensulphate $\left(\mathrm{CH}_3-\mathrm{CH}_2-\mathrm{OSO}_2-\mathrm{OH}\right)$ starting from ethanol $\left(\mathrm{C}_2 \mathrm{H}_5 \mathrm{OH}\right)$.

Explanation

For preparation of ethyl hydrogensulphate $\left(\mathrm{CH}_3-\mathrm{CH}_2-\mathrm{OSO}_2-\mathrm{OH}\right)$ starting from ethanol $\left(\mathrm{C}_2 \mathrm{H}_5 \mathrm{OH}\right)$, it is the two steps mechanism.

Step I Protonation of alcohol

Step II Attack of nucleophile

Temperature should not be allowed to rise above 383 K , otherwise diethyl ether will be produced at 413 K or ethene at 433 K .

40
Subjective

Match the reagent from Column I which on reaction with $\mathrm{CH}_3-\mathrm{CH}=\mathrm{CH}_2$ gives some product given in Column II as per the codes given below

Column I Column II
A. $\mathrm{O}_3 / \mathrm{Zn}+\mathrm{H}_2 \mathrm{O}$ 1. Acetic acid and $\mathrm{CO}_2$
B. $\mathrm{KMnO}_4 / \mathrm{H}^{+}$ 2. Propan-1-ol
C. $\mathrm{KMnO}_4 / \mathrm{OH}^{-}$ 3. Propan-2-ol
D. $\mathrm{H}_2 \mathrm{O} / \mathrm{H}^{+}$ 4. Acetaldehyde and formaldehyde
E. $\mathrm{B}_2 \mathrm{H}_6 / \mathrm{NaOH}^{+}$and $\mathrm{H}_2 \mathrm{O}_2$ 5. Propane-1, 2-diol

Explanation

A. $\rightarrow$ (4)

B. $\rightarrow$ (1)

C. $\rightarrow$ (5)

D. $\rightarrow(3)$

E. $\rightarrow(2)$

Column I Column II
A. $\mathrm{O}_3 / \mathrm{Zn}+\mathrm{H}_2 \mathrm{O}$ 1.
B. $\mathrm{KMnO}_4 / \mathrm{H}^{+}$ 2. $\mathrm{CH}_3 \mathrm{CH}=\mathrm{CH}_2 \xrightarrow[\mathrm{H}^{+}]{\mathrm{KMnO}_4} \underset{\text { Aceticacid }}{\mathrm{CH}_3 \mathrm{COOH}}+\mathrm{CO}_2$
C. $\mathrm{KMnO}_4 / \mathrm{OH}^{-}$ 3.
D. $\mathrm{H}_2 \mathrm{O} / \mathrm{H}^{+}$ 4. $\mathrm{CH}_3 \mathrm{CH}=\mathrm{CH}_2 \xrightarrow[\text { (Markn addition) }]{\mathrm{H}_2 \mathrm{O} / \mathrm{H}^{+}} \underset{\text { Propan-2-ol }}{\mathrm{CH}_3-\mathrm{CH}(\mathrm{OH})-\mathrm{CH}_3}$
E. $\mathrm{B}_2 \mathrm{H}_6 / \mathrm{NaOH}^{+}$and $\mathrm{H}_2 \mathrm{O}_2$ 5.

41
Subjective

Match the hydrocarbons in Column I with the boiling points given in Column II.

Column I Column II
A. n-pentane 1. 282.5 K
B. iso-pentane 2. 309 K
C. neo-pentane 3. 301 K

Explanation

A - (2), B - (3), C - (1)

Column I Column II
A. n-pentane 1. 309 K due to no branch
B. iso-pentane 2. 301 K due to one branch
C. neo-pentane 3. 282.5 K due to two branches

42
Subjective

Match the following reactants in Column I with the corresponding reaction products in Column II.

Column I Column II
A. Benzene $+\mathrm{Cl}_2 \xrightarrow{\mathrm{AlCl}_3}$ 1. Benzoic acid
B. Benzene $+\mathrm{CH}_3 \mathrm{Cl} \xrightarrow{\mathrm{AlCl}_3}$ 2. Methyl phenyl ketone
C. Benzene $+\mathrm{CH}_3 \mathrm{COCl} \xrightarrow{\mathrm{AlCl}_3}$ 3. Toluene
D. Toluene $\xrightarrow{\mathrm{KMnO}_4 / \mathrm{NaOH}}$ 4. Chlorobenzene
5. Benzene hexachloride

Explanation
A - (4), B - (3), C - (2), D - (1)

Reactants Products
A. Benzene $+\mathrm{Cl}_2 \xrightarrow{\mathrm{AlCl}_3}$
B. Benzene $+\mathrm{CH}_3 \mathrm{Cl} \xrightarrow{\mathrm{AlCl}_3}$
C. Benzene $+\mathrm{CH}_3 \mathrm{COCl} \xrightarrow{\mathrm{AlCl}_3}$
D. Toluene $\xrightarrow{\mathrm{KMnO}_4 / \mathrm{NaOH}}$