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Impure chloroform give white powder of ethyl carbonate by the addition of ethanol Chloroform is oxidized by air in presence of light to form Phosgene gas and HCl. 

Chloroform is converted ot methylene - chloride by the action of Zn + HCl and H₂/Ni.

Uses of Freon -12:

Freon -12 (dichlorodifluoromethane, CF₂Cl₂) is commonly known as CFC. It is used as a refrigerant in refrigerators and air conditioners. It is also used in aerosol spray propellants such as body sprays, hair sprays etc. However, it damages the ozone layer. Hence its manufacture is banned.

Uses of DDT:

DDT (p, p – dichlorodiphenylchloroethane) is one of the best known pesticides. It is very effective against mosquito and lice. However, due to its harmful effects, its manufacture is banned;

Uses of carbon tetrachlorides (CCl₄):

• It is used for manufacturing refrigerants and propellants for aerosol cans.
• It is used as feedstock in the synthesis of CFCs and other chemicals.
• It is used as a solvent in the manufacture of pharmaceutical products.
• CCl₄ was once widely used as a cleaning fluid, a degreasing agent in industries, a spot remover homes, and a fire extinguisher.

Uses of iodoform (CHI₃):

Iodoform was used as an antiseptic, but now it has been replaced by other formulations containing iodine-due to its objectionable smell. The antiseptic property of CHI₃ is only due to the liberation of free iodine when it comes in contact with the skin.

(c) chloropicrin

Grignard reagent react with H₂O to form alkanes , therefore they are prepared under anhydrous condition. 

Correct answer is (c) benzene

Due to resonance the carbon- oxygen bond in phenols has partial double bond and it is stronger than carbon oxygen single bond.  

KCN is ionic they can attach through C or N but C-C bond is strong than C-N bond. So alkyl cyanide is the major product but AgCN is covalent so more electronegative N can attach to C and forms isocyanides.  

-NO₂ group is electron with - drawing group, e- density on O decreases and loss of H⁺ is easy whereas –OCH₃ group is electron releasing group , which increases e- density on O , which makes difficult to the loss of H⁺, hence are less acidic . 

Chloro (or) bromoalkanes on heating with AgF give fluoroalkanes. This reaction is called Swans reaction.

CH₃ (Ethanol) - CH₂ + Br + AgF \(\overset{Δ}{\longrightarrow}\) CH₃ - CH₂F(Fluoroethane) + AgBr

Chloro (or) bromoalkane on heating with sodium iodide in dry acetone gives jodo alkane. This reaction is called Finkeistein reaction.

CH₃ (Bromoethane) - CH₂Br + NaI → CH₃ - CH₂I(Iodoethane) + NaBr

Hydride ion/H^-

Correct answer is (b) HCHO

Alkyl halides though polar are immiscible with water because less energy is released when new attractions are set up between the alkyl halide and the water molecules as they are not as strong as the original hydrogen bonds in the water as a result the solubility of alkyl halides in water is low.

2,4,6- Tribornoaniline/2,4,6- Tribromobenzenamine.

(i), (iii)

(i) (CH₃)₂ CHBr

(iii) CH₃CH(Br)CH₂CH₃

(i), (iv)

(i) p-ClC₆H₄CH₂CH(CH₃)₂  

(iv) C₆H₅-Cl

(i), (ii)

(i) HCl + ZnCl₂

(ii) Red P + Br₂

(d) HF It is not used to prepare directly fluoro alkane whereas others are used to prepare directly chloro alkanes.

(i) CH₃ - CH₂OH (Ethanol) + PCl₅ → CH₃ - CH₂Cl (Ethyl chloride) + POCl₃ + HCl

(ii) 3CH₃ - CH₂OH (Ethanol) + PCl₃ → 3CH₃-CH₂Cl(Ethyl chloride) + H₃PO₃

Freons are the chiorofluoro derivatives of methane and ethane. 

Freon is represented as Freon – cba 

Where, c = number of carbon atoms, 

b = number of hydrogen atoms, 

a = total number of fluorine atoms. 

CF₂Cl₂ = 0 

c = 1 – 1 = 0

H = 0 +1 = 1 

F = 2

So Freon – 12 is CF₂Cl₂

Uses of Freons: 

• Freons are used as refrigerants in refrigerators and air conditioners. 
• it is used as a propellant for aerosols and foams. 
• it is used as propellant for foams to spray out deodorants, shaving creams and insecticides.

Environmental effects of Freons: 

1. Freon gas is a very powerful greenhouse gas which means that it traps the heat normally radiated from the earth out into the space. This causes the earth’s temperature to increase, resulting in rising sea levels, droughts. stronger storms, flash floods and a host of other very unpleasant effect .

2. As freon moves throughout the air, its chemical ingredients causes depletion of ozone layer. Depletion of ozone increases the amount of ultraviolet radiations that reaches the earths surface, resulting in serious risk to human health. High levels of ozone, in turn, causes resoiratory problems and can also kill olants.

• Freons are used as refrigerants in refrigerators and air conditioners. 
• It is used as a propellant for foams and aerosols. 
• It is used as a propellant for foams to spray out deodorants, shaving creams and insecticides.

In S_N¹ reaction, carbocation intermediate formed is a planar molecule which will lead to form d - and I- products. Hence racemization occurs.

Chloromethane < Bromomethane < Dibromomethane < Bromoform.

DDT is used to kill various insects like housefly and mosquitoes.

This is because alkylhalides can neither make or break hydrogen bonds with water molecules.

2-iodo-2-methylpropane belongs to type 3°haloalkanes.

2-Brotmo-2-methylbutane.

Primary alkyl halides prefer to undergo substitution reaction by S_N2 mechanism whereas tertiary halides undergo elimination reaction due to the formation of stable carbocation.

C₆H₅N₂CI (Benzene diazonium chloride)+ KI \(\overset{warm}{\longrightarrow}\) C₆H₅I (Iodo benzene) + KCI + N₂↑

2-Bromo-2-methylbutane

Detailed Answer:

2-Bromo-2-methylbutane as tertiary alkyl halide is most reactive for eliminations

2-Bromopentane

Detailed Answer:

2-Bromopentane as it contains unsymmetrical carbon atom.

(i), (ii)

(i) The given reaction follows S_N2 mechanism.

(ii) (b) and (d) have opposite configuration.

(i), (iii)

(i) Ethylidene chloride

(iii) Methylene chloride

(i), (iii)

(i) Both the compounds form same product on treatment with alcoholic KOH.

(iii) Both the compounds form same product on reduction.

Cl CH₂CH₂Cl (Ethylene Chloride) Vicinal Dihalides

CH₃CHCl₂ (Ethylidene chloride) Gem Dihalides 

(i), (iv)

(i) Intermediate (c) is unstable because in this carbon is attached to 5 atoms.

(iv) Intermediate (c) is less stable than the reactant (b).

The reactivity of haloacids (HCl , HBr, HI) with alcohol is in the order HI > HBr > HCl.

3- Chloropropene 

(a) Methane gets converted to CCl₄. 

(b) Because of release of chorine vapors in the atmosphere. 

(c) Appropriate knowledge of organic chemical is essential while handling them. 

1- Chloro-2,2 -dimethylpropane

CH₃CI as 1°  alkyl halides are more reactive than tert-alkyl halides in S_N² reaction with OH^-.

CH₃I as I^- ion is better leaving group than Br^- ion.

The mentioned halo compounds belong to the class of polyhalogen compounds. 

Dichloromethane: It is used as a solvent, as a paint remover, as a propellant in aerosols and as a process solvent in the manufacture of drugs. It is also used as a metal cleaning and finishing solvent. Trichloromethane It is employed as a solvent for fats, alkaloids, iodine and other^ubstances. Triiodomethane It is used as an antiseptic. Now, it has been replaced by some other compounds because of its objectionable smell.  

But some compounds of this class are responsible for exposure of flora and fauna to more and more of UV light which causes destruction to great extent. 

These are as follows: 

(i) Tetrachloromethane When carbon tetrachloride is released into the air, it rises to the atmosphere and depletes the ozone layer. Depletion of the ozone layer is believed to increase human exposure to UV rays leading to increased skin cancer, eye diseases and disorders, and possible disruption of the immune system. These UV rays cause damage to plants, and reduction of plankton populations in the ocean’s photic zone. 

(ii) Freons Freon-113 is likely to remain in the air long enough to reach the upper atmosphere. Here, it provides chlorine atoms which damage the ozone layer. Because of this depletion, UV rays enters in our atmosphere and become responsible for the damage to great extent. 

(iii) p-p’-dichlorodiphenyltrichloroethane (DDT) It is non-biodegradable. Instead, it gets deposited in fatty tissues. If ingestion continues for a long time, DDT builds up within the animal and affect the reproductive system. To minimise the harmful impacts of these compounds (i.e. freons, hydrofluorocarbons), fluorocarbons and hydrocarbons can be straight used to make refrigerants and air-conditioning equipment. They are stable in the stratosphere and are safe for flora and fauna.