Anhydrous Ferric Chloride (FeCl₃) is another Lewis acid which can be used.

Boiling points of alkanes
1. The boiling points of alkanes rise as the number of carbons increases.
2. Since nonane has a longer carbon chain than octane, it will have a higher boiling point.
Effect of branching on the boiling point of alkane
1. As an alkane chain branch, the surface area of the molecule decreases.
2. The intermolecular force reduces as a result of this.
3. At a lower temperature, the forces can be readily overcome.
4. Therefore, as the branching increases, the boiling point of an alkane chain decreases.

Butanoic acid,
\(\mathrm{CH}_3 \mathrm{CH}_2 \mathrm{CH}_2 \mathrm{COO}^{-} \mathrm{Na}^{+}+\mathrm{NaOH} \stackrel{\mathrm{CaO}}{\longrightarrow}  \mathrm{CH}_3 \mathrm{CH}_2 \mathrm{CH}_3+\mathrm{Na}_2 \mathrm{CO}_3\)

Alkenes are rich source of loosely held \(\pi \) electrons, due to which they show electrophilic addition reaction. Electrophilic addition reactions of alkenes are accompanied by large energy changes so these are energetically favourable than that of Electrophilic substitution reactions.
In special conditions alkenes also undergo free radical substitution reactions.
In arenes during electrophilic addition reactions aromatic character of benzene ring is destroyed while during electrophilic substitution reactions of areans are enegetically more favourable than that of electrophilic addition reaction.
That's why alkenes prefer to undergo electrophilic addition reaction while arenes prefer electrophilic substitution reactions.

On converting benzene to toluene, there is a fall in the melting point although toluene has the higher molecular mass. This is because the planar molecules of benzene can pack more closely in the crystal lattice and the cohesive forces are strong, whereas the methyl group in toluene prevents such close packing.

For exhibiting cis-trans (or geometrical isomerism, a molecule must fulfil the following condition.
The groups attached to each double bonded carbon atom must be different.

For exhibiting cis-trans (or geometrical isomerism, a molecule must fulfil the following condition.
It must have atlest one double bond.

(ii) Ethene is first converted into ethyne and then to benzene as shown above.

(iii) When vapours of hexane are passed over heated catalyst consisting of Cr₂ O₃, MO₂O₃ and V₂O₅ at 773 K under 10-20 atm pressure, cyclization and aromatization occurs simultaneously to afford benzene

Addition of HBr to propene is an ionic electrophilic addition reaction in which the electrophile, i.e., H+ first adds to give a more stable 2° carbocation. In the 2nd step, the carbocation is rapidly attacked by the nucleophile Br^- ion to give 2-bromopropane.

In presence of benzoyl peroxide, the reaction is still electrophilic but the electrophile here is a Br free radical which is obtained by the action of benzoyl peroxide on HBr

In the first step, Br radical adds to propene in such a way so as to generate the more stable 2° free radical. In the second step, the free radical thus obtained rapidly abstracts a hydrogen atom from HBr to give 1-bromopropane.

From the above discussion, it is evident that although both reactions are electrophilic addition reactions but it is due to different order of addition of H and Br atoms which gives different products.

(i)  \({ C }_{ 4 }{ H }_{ 10 }+13/2(g)\overset { \Delta }{ \longrightarrow } 4C{ O }_{ 2 }(g)+5{ H }_{ 2 }O(g)\)
     Butane
(ii) \({ C }_{ 5 }{ H }_{ 10 }(g)+15/2{ O }_{ 2 }(g)\overset { \Delta }{ \longrightarrow } 5{ CO }_{ 2 }(g)+5{ H }_{ 2 }O(g)\)
     Pentene
(iii) \({ C }_{ 6 }{ H }_{ 10 }(g)+17/{ 2O }_{ 2 }(g)\overset { \Delta }{ \longrightarrow } 6{ CO }_{ 2 }(g)+{ 5H }_{ 2 }O(g)\)
    Hexyne
(iv) 

(i) \(\overset { 5 }{ C } { H }_{ 3 }-\overset { 4 }{ C } H_{ 2 }-\overset { 3 }{ C } H=\overset { 2 }{ C } H\overset { 1 }{ C } { H }_{ 3 }\overset { (i){ O }_{ 3 }/{ CH }_{ 2 }{ CI }_{ 2 },196\quad K }{ \underset { (ii)\quad Zn/{ H }_{ 2 }O }{ \longrightarrow } } { CH }_{ 3 }-{ CH }_{ 2 }-CH=O+O=CH-{ CH }_{ 3 }\)
                       Pent-2-ene                                                                                 Propanal                                Ethanal

(iv) \({ \overset { 4 }{ C } }H_{ 3 }\overset { 3 }{ C } { H }_{ 2 }-\overset { 2 }{ C } H=\overset { 1 }{ C } { H }_{ 2 }-{ C }_{ 6 }{ CH }_{ 5 }\overset { (i){ O }_{ 3 },{ CH }_{ 2 }{ C1 }_{ 2 },196\quad K }{ \underset { (ii)Zn/{ H }_{ 2 }O }{ \longrightarrow } } { CH }_{ 3 }{ CH }_{ 2 }CH=0+0=CH-{ C }_{ 6 }{ H }_{ 5 }\)
                   1-Phenylbut-1-ene                                                               Propanal                              Benzaldehyde

The basic skeleton 2-methylbutane is 

Putting double bonds at various different positions and satisfying the tetracovalency of each carbon, the structures of various alkenes which give 2-methylbutane on hydrogenation are:

The necessary conditions for a molecule to be aromatic are:
(i) It should have a single cyclic cloud of delocalised \(\pi\)-electrons above and below the plane of the molecule.
(ii) It should be planar. This is because complete delocalization of \(\pi\)-electrons is possible only if the ring is planar to allow cyclic overlap of p-orbitals.
(iii) It should contain Huckel number of electrons, i.e., (4n + 2) \(\pi\)-electrons where n = 0, 1, 2, 3 ................ etc.
A molecule which does not satisfy any one or more of the above conditions is said to be non-aromatic.

(i) Write the structures of prop anal and pentan-3-ene with their oxygen atoms facing each other, we have,

(ii) Removeoxygen atoms and join the two fragments by a double bond, the structure of the alkene is