i) DDT: DDT can be prepared by heating a mixture of chlorobenzene with chloral (Trichloro acetaldehyde) in the presence of con. H₂SO₄,

ii) Chloroform :The reaction of methane with excess of chlorine in the presence of sunlight will give carbon tetrachloride as the major product.
\(\underset { Methane }{ { CH }_{ 4 }+4C{ l }_{ 2 }\overset { h\gamma }{ \longrightarrow } } +\underset { Carbon \ tetrachloride }{ 4HCl } \)
iii) Bipheenyl :
\(\underset { Chlorobenzene }{ { C }_{ 6 }{ H }_{ 5 }Cl } +2Na+Cl-{ C }_{ 6 }{ H }_{ 5 }\overset { Ether }{ \longrightarrow } \underset { Biphenyl }{ { C }_{ 6 }{ H }_{ 5 }-{ C }_{ 6 }{ H }_{ 5 }+2NaCl } \)
iv) Chloropicrin : Chloroform reacts with nitric acid to form chloropicrin.(Trichloro nitro methane)
\(\underset { Chloroform }{ { CH }_{ 3 }+HN{ O }_{ 3 }\overset { \triangle }{ \longrightarrow } } \underset { Chloropicrin }{ C{ Cl }_{ 3 }N{ O }_{ 2 }+{ H }_{ 2 }O } \)
v) Freon-12 :Freon - 12 is prepared by the action of hydrogen fluoride on carbon tetrachloride in . the presence of catalylic amount of antimony pentachloride. is is called swartz reaction
\(\underset { Carbontetrachloridew }{ { CCl }_{ 3 }+2HF\overset { SbC{ l }_{ 5 } }{ \longrightarrow } } \underset { Freon-12 }{ 2HC{ l }+CCl_{ 2 }F_{ 2 } } \)

The rate of the following SN₁ reaction depends upon the concentration of alkyl halide (RX) and is independent of the concentration of the nucleophile (OH-).
Hence Rate of the reaction = k [alkyl halide]
SN₁ reaction mechanism by taking a reaction between tertiary butyl bromide with aqueous KOH.
\({ CH }_{ 3 }-\overset { \underset { | }{ { CH }_{ 3 } } }{ \underset { \overset { | }{ { CH }_{ 3 } } }{ C } } -Br\overset { { OH }^{ - }(aq) }{ \underset { -Br }{ \longrightarrow } } { CH }_{ 3 }-\overset { \underset { | }{ { CH }_{ 3 } } }{ \underset { \overset { | }{ { CH }_{ 3 } } }{ C } } -OH\)
Tert-Butyl bromide                           Tert-Butyl alcohol
This reaction takes place in two steps as shown below
Step-1 Formation of carbocation :
The polar C - Br bond breaks forming a carbocation and bromide ion. is step is slow and hence it is the rate determining step

The carbocation has 2 equivalent lobes of the vacant 2p orbital, so it can react equally rapidly from either face
Ste - 2
The nucleophile immediately reacts with the carbocation. This step is fast and hence does not affect the rate of the reactions.

As shown above, the nucleophilic reagent OH^- can attack carbocation from both the sides.

(i) Freon - 12 is prepared by the action of hydrogen fluoride on carbon tetrachloride in the presence "of catalylic amount of antimony pentachloride. is is called swartz reaction.
\(\underset { Carbontetrachloride }{ C{ Cl }_{ 4 }+2HF } \overset { SbC{ l }_{ 5 } }{ \longrightarrow } \underset { Freon-12 }{ 2HCl } +CC{ l }_{ 2 }{ F }_{ 2 }\)
(ii) Carbon disulphide reacts with chlorine gas in the presence of anhydrous AICl₃ as catalyst giving carbon tetrachloride
\(\underset { carbondisulphide }{ { CS }_{ 2 }+3C{ l }_{ 2 }\overset { anhydrous }{ \underset { Al{ Cl }_{ 3 } }{ \longrightarrow } } } \underset { Carbontetrachloride }{ { CCl }_{ 4 }+{ S }_{ 2 }{ Cl }_{ 2 } } \)

If moisture is present, the Grignard reagent will react with water to give alkanes.

So. moisture should not be present

Carbon halogen bond is a polar bond as halogens are more electro negative than carbon. The carbon atom exhibits a partial positive charge (\(\delta \)+) and halogen atom a partial negative charge (\(\delta \)-)
The C -X bond is formed by overlap of sp³ orbital of carbon atom I with half filled p-orbitat of the halogen atom. The atomic size of halogen increases from fluorine to iodine, which increases the C - X bond length. Larger the size, greater is the bond length, and weaker is the bond formed. The bond strength of C - X decreases from C - F to C - I in CH₃X

The Chlorination of methane is carried out by free radical mechanism. The initiation step to form free radical needs high energy which is supplied by light energy.
\(\mathrm{Cl}-\mathrm{Cl} \stackrel{h \nu}{\longrightarrow} 2 \mathrm{Cl}\)
So this reaction is not possible in dark.

\(\overset { \underset { | }{ Cl } }{ \underset { \overset { | }{ Cl } }{ CH } } -{ CH }_{ 3 }\quad (A)\) 1, 1,-dichloro ethane
\(\underset { \overset { | }{ Cl } }{ { CH }_{ 2 } } -\underset { \overset { | }{ Cl } }{ { CH }_{ 2 } } \) (B) 1, 2, dichloro ethane
\(\overset { \underset { | }{ Cl } }{ \underset { \overset { | }{ Cl } }{ CH } } -{ CH }_{ 3 }\underset { aq\quad KOH }{ \longrightarrow } \left[ \overset { \underset { | }{ OH } }{ \underset { \overset { | }{ OH } }{ CH } } -{ CH }_{ 3 } \right] \underset { -{ H }_{ 2 }) }{ \longrightarrow } { CH }_{ 3 }CHO\)
(A)                                                                    (C)
1, 1, dichloro ethane                                      Acetaldhyde
\(A \ \ \overset { \underset { | }{ Cl } }{ \underset { \overset { | }{ Cl } }{ CH } } -{ CH }_{ 3 }\)  -1,1 dichloro ethane
B  \(\underset { \overset { | }{ Cl } }{ { CH }_{ 2 } } -\underset { \overset { | }{ Cl } }{ { CH }_{ 2 } } \)-1, 2 dichloro ethane
C CH₃CHO -Acetaldehyde 
D \(\underset { \overset { | }{ OH } }{ { CH }_{ 2 } } -\underset { \overset { | }{ OH } }{ { CH }_{ 2 } } \)-Ethyleneglycol

With acetyl chloride, CH₃MgI given first acetone.

The acetone formed will react with excess CH₃MgI to give a tertiary alcohol, t - butyl alcohol.