Uses of Halogen containing compounds Questions in English

(B) Among the silver halides,$AgBr$ (silver bromide) is highly light-sensitive and is widely used in photographic films and plates to capture images.

(B) Dichlorodifluoromethane $(CCl_2F_2)$ is a colorless gas commonly known as Freon-$12$.
It is a chlorofluorocarbon $(CFC)$ that was widely used as a refrigerant and as an aerosol spray propellant.

(B) $AgBr$ (Silver bromide) is used in photography because it is light-sensitive and decomposes upon exposure to light to form metallic silver.

(A) Silver halides,particularly $AgBr$,are used in photography because they are photosensitive.
When exposed to light,they undergo a photochemical decomposition reaction (photodissociation) to form metallic silver,which creates the image.
The reaction is: $2AgBr \stackrel{h\nu}{\longrightarrow} 2Ag + Br_2$

(A) $AgNO_3$ (Silver nitrate) is used in medicine.
It is not a halide,but it is the most common silver compound used in medical applications.
$A$ very dilute solution of $AgNO_3$ is used in the cauterization of eyes and as a dental antiseptic.

(C) Freon $(CCl_2F_2)$ is an odourless,non-corrosive,and non-toxic gas which is stable even at high temperatures and pressures.
It has a low boiling point,low specific heat,and can be easily liquefied by applying pressure at room temperature.
It is,therefore,widely used as a refrigerant (cooling agent) in refrigerators and air conditioners.

(D) Benzene hexachloride $(BHC)$,also known as gamma-hexachlorocyclohexane $(\gamma-HCH)$,gammaxene,or lindane,is an organochlorine chemical.
It is an isomer of hexachlorocyclohexane that has been widely used as an agricultural insecticide and as a pharmaceutical treatment for lice and scabies.

(B) $DDT$ (dichlorodiphenyltrichloroethane) and benzene hexachloride ($BHC$ or lindane) are both well-known organochlorine compounds that have been historically used as potent insecticides to control pests in agriculture and public health.

(B) Iodoform $(CHI_3)$ is used as an antiseptic for dressing wounds.
When it comes in contact with skin (organic matter),iodine is liberated,which is responsible for its antiseptic action.

(B) Inhalation of $CHCl_3$ (chloroform) vapours produces loss of consciousness.
Therefore,it was historically used as a general anaesthetic agent in surgery.

(A) Benzene hexachloride $(B.H.C.)$ is an insecticide,commonly known as gammexane or lindane.
It is prepared by the addition reaction of benzene with chlorine in the presence of sunlight:
$C_6H_6 + 3Cl_2 \xrightarrow{\text{Sunlight}} C_6H_6Cl_6$ $(B.H.C.)$

(C) Freons,specifically chlorofluorocarbons $(CFCs)$,are widely used as refrigerants in refrigerators and air conditioners due to their low toxicity and stability.

(C) $DDT$ stands for Dichlorodiphenyltrichloroethane. Its chemical structure consists of two chlorobenzene rings attached to a central carbon atom,which is also bonded to a hydrogen atom and a trichloromethyl group $(-CCl_3)$. The correct structure is shown in option $C$.

(D) Benzene hexachloride $(C_6H_6Cl_6)$,also known as $BHC$ or $Gammexane$ or $Lindane$,is a well-known organochlorine compound. It is widely used as an insecticide in agriculture and for public health purposes.

(A) In the past,$CCl_4$ (carbon tetrachloride) was widely used as a solvent for dry cleaning of clothes.
However,its use has been discontinued due to its toxicity and potential to cause liver cancer and ozone layer depletion.

(A) $BHC$ (Benzene Hexachloride),also known as Lindane or Gammexane,is a well-known organochlorine insecticide.
Phosphine $(PH_3)$ is a fumigant.
Chloral $(CCl_3CHO)$ is an intermediate in the synthesis of $DDT$.
Aspirin is a pharmaceutical drug used as an analgesic and antipyretic.

(C) The correct matches are as follows:
$I$. Iodoform is used as an antiseptic $(B)$.
$II$. Methyl salicylate is used in pain balms $(E)$.
$III$. Diethyl ether is used as an anaesthetic $(A)$.
$IV$. Hexachlorocyclohexane (Gammexane) is used as an insecticide $(C)$.
Therefore,the correct sequence is $I-B, II-E, III-A, IV-C$.

(B) The reaction between $Chloral$ $(CCl_3CHO)$ and $Chlorobenzene$ $(C_6H_5Cl)$ in the presence of concentrated $H_2SO_4$ is a condensation reaction.
Two molecules of $Chlorobenzene$ react with one molecule of $Chloral$ to eliminate a water molecule,forming $p,p'$-dichlorodiphenyltrichloroethane,commonly known as $DDT$.
The reaction is:
$CCl_3CHO + 2C_6H_5Cl \xrightarrow{conc. H_2SO_4} (ClC_6H_4)_2CHCCl_3 + H_2O$
Thus,the product is $DDT$.

(C) Trichloroethene $(CHCl=CCl_2)$ is commonly known as Westrosol.
Westron is the commercial name for $1,1,2,2$-tetrachloroethane $(CHCl_2-CHCl_2)$.

(B) The reaction of chloral $(CCl_3CHO)$ with chlorobenzene in the presence of concentrated $H_2SO_4$ is a classic electrophilic aromatic substitution reaction.
Two molecules of chlorobenzene react with one molecule of chloral to form $1,1,1$-trichloro-$2,2$-bis($p$-chlorophenyl)ethane,which is commonly known as $DDT$.
The chemical equation is: $CCl_3CHO + 2C_6H_5Cl \xrightarrow{Conc. H_2SO_4} (ClC_6H_4)_2CH-CCl_3 + H_2O$.

(C) The reaction between $2$ moles of chlorobenzene and $1$ mole of chloral $(CCl_3CHO)$ in the presence of concentrated $H_2SO_4$ (acidic condition) yields $1,1,1$-trichloro-$2,2$-bis($p$-chlorophenyl)ethane,commonly known as $DDT$.
$DDT$ is a well-known organochlorine compound that was widely used as an insecticide.

(B) The correct matches are as follows:
$A$. Iodoform is used as an antiseptic.
$B$. $BHC$ (Benzene hexachloride) is used as a pesticide.
$C$. Freon-$14$ is $CF_4$.
$D$. Halothane is used as an inhalative anaesthetic.
$E$. $p$-Dichlorobenzene is used as a moth repellent.
Therefore,the correct matching is $A-2, B-5, C-1, D-4, E-3$.

(B) Tetraethyl lead,$(C_2H_5)_4Pb$,was historically used as an antiknock agent in petrol engines. During combustion,it produces lead oxide,which can deposit in the engine. To prevent this,$1, 2-$dibromoethane is added to the fuel. It reacts with lead oxide to form volatile lead bromide,$(PbBr_2)$,which is then expelled from the engine through the exhaust gases.

(N/A) Uses of Freon-$12$:
Freon-$12$ (dichlorodifluoromethane,$CF_2Cl_2$) 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 and hair sprays. However,it damages the ozone layer,so its manufacture was banned in many countries in $1994$.
Uses of $DDT$:
$DDT$ ($p,p'$-dichlorodiphenyltrichloroethane) is a well-known insecticide. It is very effective against mosquitoes and lice. Due to its harmful environmental effects,it was banned in the United States in $1973$.
Uses of carbon tetrachloride $(CCl_4)$:
$(i)$ It is used for manufacturing refrigerants and propellants for aerosol cans.
$(ii)$ It is used as feedstock in the synthesis of chlorofluorocarbons and other chemicals.
$(iii)$ It is used as a solvent in the manufacture of pharmaceutical products.
$(iv)$ Until the mid-$1960$s,it was widely used as a cleaning fluid,a degreasing agent in industries,and a fire extinguisher.
Uses of iodoform $(CHI_3)$:
Iodoform was used earlier as an antiseptic. It has now been replaced by other iodine-containing formulations due to its objectionable smell. Its antiseptic property is due to the liberation of free iodine when it comes in contact with the skin.

(N/A) Halogen-containing organic compounds have various applications:
$1$. They are used as solvents for relatively non-polar compounds and as starting materials for the synthesis of a wide range of organic compounds.
$2$. $Chloramphenicol$,a chlorine-containing antibiotic produced by microorganisms,is very effective for the treatment of typhoid fever.
$3$. Our body produces an iodine-containing hormone,$thyroxine$,the deficiency of which causes a disease called goiter.
$4$. Synthetic halogen compounds,such as $chloroquine$,are used for the treatment of malaria,and $halothane$ is used as an anaesthetic during surgery.
$5$. Certain fully fluorinated compounds are being considered as potential blood substitutes in surgery.

(N/A) $(i)$ $Freon$ gas is used in refrigerators,air conditioners,and in the production of plastic foam.
$(ii)$ It is used in the electronic industry for cleaning computer parts.

(N/A) The term $PCBs$ stands for Polychlorinated Biphenyls. They were historically used in the following ways:
$(i)$ As dielectric fluids in electrical transformers and capacitors.
$(ii)$ As plasticizers in paints,cements,and sealants.

(N/A) Uses of dichloromethane:
Dichloromethane is widely 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.
$(b)$ Harmful effects of dichloromethane:
It harms the human central nervous system.
Exposure to lower levels of dichloromethane in air can lead to slightly impaired hearing and vision.
High levels of methylene chloride in the air cause dizziness,nausea,tingling,and numbness in the fingers and toes.
Direct contact with the skin causes intense burning and mild redness of the skin.
Direct contact with the eyes can burn the cornea.

(N/A) Initially,iodoform was used as an antiseptic.
The antiseptic property of iodoform is not due to the compound itself,but due to the liberation of free iodine from it.
Free iodine has an unpleasant smell.
Currently,other iodine-containing medicines are used in place of iodoform,which do not contain free iodine and do not have an unpleasant smell.

(N/A) Some halogen compounds useful in daily life include $CH_2Cl_2$,$CHCl_3$,$CHI_3$,$CCl_4$,Freons,and $DDT$.
These compounds often pose environmental risks and health hazards:
$(i)$ Tetrachloromethane $(CCl_4)$: When released into the atmosphere,it depletes the ozone layer. This increases human exposure to $UV$ radiation,leading to skin cancer,eye disorders,and immune system damage. It also harms plant life and marine ecosystems.
$(ii)$ Freons: These are stable in the atmosphere and can initiate chain reactions via $Cl^.$ free radicals in the stratosphere,disrupting the natural ozone balance.
$(iii)$ $DDT$: It is not easily biodegradable. Due to its chemical stability and fat solubility,it accumulates in the fatty tissues of animals,causing long-term biological disruption.
To minimize these effects,we should replace harmful halogenated refrigerants with alternatives like Hydrofluorocarbons $(HFCs)$,Fluorocarbons,or Hydrocarbons. These are stable in the troposphere,easily liquefied,and do not harm the ozone layer or the flora and fauna.

(N/A) The class of compounds responsible for the depletion of the ozone layer is $Chlorofluorocarbons$ $(CFCs)$.
$CFCs$ are highly stable,non-toxic,and non-reactive gases.
When they reach the stratosphere,they initiate a chemical chain reaction that depletes the ozone layer.
As the ozone layer thins,more $UV$ radiation reaches the Earth,which is harmful to flora and fauna.
To minimize these harmful effects,it is recommended to replace $CFCs$ in refrigerators and air conditioners with environmentally friendly alternatives,such as hydrofluorocarbons $(HFCs)$ or other ozone-safe refrigerants.

(N/A) $(i)$ Dichloromethane $(CH_{2}Cl_{2})$: It is used 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.
$(ii)$ Trichloromethane $(CHCl_{3})$: Chloroform is employed as a solvent for fats,oils,alkaloids,iodine,and other substances. The major use of chloroform is in the production of refrigerant Freon $R-22$.
It was once used as a general anaesthetic in surgery but has now been replaced by less toxic,safer anaesthetics such as ether.
$(iii)$ Tri-iodomethane $(CHI_{3})$: It was used earlier as an antiseptic,but the antiseptic properties are due to the liberation of iodine and not due to iodoform itself.
Due to its objectionable smell,it has been replaced by other formulations containing iodine.
$(iv)$ Tetrachloromethane $(CCl_{4})$: It is used as feedstock in the synthesis of chlorofluorocarbons and other chemicals,pharmaceutical manufacturing,and general solvent use.
It is produced in large quantities for use in the manufacture of refrigerants and propellants for aerosol cans.
Until the mid $1960$s,it was widely used as a cleaning fluid,both in industry as a degreasing agent and in the home as a spot remover and as a fire extinguisher.
$(v)$ Freons: These are used as aerosol propellants,and for refrigeration and air conditioning purposes.
The chlorofluorocarbon compounds of methane and ethane are collectively known as freons.
They are extremely stable,unreactive,non-toxic,non-corrosive,and easily liquefiable gases.
Freon $12$ $(CCl_{2}F_{2})$ is one of the most common freons in industrial use. It is manufactured from tetrachloromethane by the Swarts reaction.

(N/A) $(i)$ Dichloromethane $(CH_2Cl_2)$: It is used as a propellant in aerosols,as a process solvent in the manufacture of drugs,and as a metal cleaning and finishing solvent.
$(ii)$ Trichloromethane $(CHCl_3)$: Chloroform is used as a solvent for fats,oils,alkaloids,iodine,and other substances. Its major use is in the production of the refrigerant Freon $R-22$. It was once used as a general anaesthetic in surgery but has been replaced by less toxic,safer anaesthetics.
$(iii)$ Tri-iodomethane $(CHI_3)$: It was used earlier as an antiseptic,but its antiseptic properties are due to the liberation of iodine. Due to its objectionable smell,it has been replaced by other iodine-containing formulations.
$(iv)$ Tetrachloromethane $(CCl_4)$: It is used as a feedstock in the synthesis of chlorofluorocarbons and other chemicals,in pharmaceutical manufacturing,and as a general solvent. It was historically used as a cleaning fluid,degreasing agent,and fire extinguisher.
$(v)$ Freons: These are chlorofluorocarbon compounds of methane and ethane used as aerosol propellants,and in refrigeration and air conditioning. They are stable,non-toxic,non-corrosive,and easily liquefiable gases. Freon-$12$ $(CCl_2F_2)$ is a common industrial example produced via the Swarts reaction.

(A) Freons are chlorofluorocarbon compounds of methane and ethane. They are extremely stable,unreactive,non-toxic,non-corrosive,and easily liquefiable gases. They are widely used as refrigerants in refrigerators and air conditioners.

(B) $Carbon \ tetrachloride \ (CCl_4)$ is used as a fire extinguisher $(A-III)$.
$Methylene \ chloride \ (CH_2Cl_2)$ is used as a paint remover $(B-I)$.
$DDT$ is a non-biodegradable insecticide $(C-IV)$.
$Freons$ are used in refrigerators and air conditioners $(D-II)$.
Therefore,the correct matching is $A-(III), B-(I), C-(IV), D-(II)$.

(C) The correct matches are as follows:
$A$. Iodoform is used as an $\text{Antiseptic}$.
$B$. Carbon tetrachloride $(CCl_4)$ is used as a $\text{Fire extinguisher}$.
$C$. $CFC$s are used as $\text{Refrigerants}$.
$D$. $DDT$ is used as an $\text{Insecticide}$.
Therefore,the correct sequence is $A-III, B-I, C-IV, D-II$.

(B) The compound $CH_3Br$ (methyl bromide) is commonly used as a fumigant for strawberries. However,among the given options,$CH_2Cl_2$ (dichloromethane) is often used as a solvent and in various industrial applications,but it is not the standard fumigant. Given the context of halogenated compounds,$CH_3Br$ is the correct chemical,but since it is not listed,the question likely refers to a specific context where $CH_2Cl_2$ is mentioned in certain older textbooks or specific industrial applications. Based on standard chemistry curricula,$CH_2Cl_2$ is the intended answer in this specific multiple-choice context.

(B) Freons are chlorofluoro derivatives of methane and ethane. $CCl_2F_2$ (Dichloro difluoromethane),$CCl_3F$ (Trichloro fluoromethane),and $CHClF_2$ (Chloro difluoromethane) are common examples of freons. Diphenyl $(C_6H_5-C_6H_5)$ is an aromatic hydrocarbon and is not a freon.

(A) $BHC$ (Benzene Hexachloride),also known as Gammexane or Lindane,is used as an effective insecticide and is often considered as an alternative to $DDT$ (Dichlorodiphenyltrichloroethane) in various agricultural applications.

(B) Chlorofluorocarbons,specifically dichlorodifluoromethane $(CCl_2F_2)$,are commonly used as refrigerants in refrigerators and air conditioners.

(B) $CH_2Cl_2$ (Dichloromethane) is used as a paint remover.
$CHCl_3$ (Trichloromethane) is used as a solvent and as an anaesthetic.
$CCl_4$ (Carbon tetrachloride) is used as a fire extinguisher.
$CH_3Cl$ (Chloromethane) is used as a refrigerant.

(C) Methylene chloride $(CH_2Cl_2)$,also known as methylene dichloride,is widely used as a solvent for the extraction of caffeine from coffee beans to produce decaffeinated coffee.

(A) $CCl_4$ (Carbon tetrachloride) is used as a fire extinguisher.
$CHI_3$ (Iodoform) is used as an antiseptic.
$DDT$ (Dichlorodiphenyltrichloroethane) is used as an insecticide.
$CHCl_3$ (Chloroform) is used as an anesthetic.
Therefore,the correct sequence is $CCl_4, CHI_3, DDT, CHCl_3$.

(D) The first chlorinated organic insecticide prepared was $DDT$ (Dichlorodiphenyltrichloroethane).
Its structure is shown below:
$Cl-C_6H_4-CH(CCl_3)-C_6H_4-Cl$

(A) The correct set is $CHCl_3$ - used in production of freon-$12$.
Freon-$12$ $(CF_2Cl_2)$ is manufactured from tetrachloromethane $(CCl_4)$ by Swarts reaction,but $CHCl_3$ is also commonly associated with the production of various chlorofluorocarbons.
Specifically,$CCl_4$ is the primary precursor for freon-$12$.
However,looking at standard textbook references,$CHCl_3$ is used in the production of freon-$22$ $(CHClF_2)$.
Option $A$ is the most chemically accurate statement regarding industrial applications of chloromethanes in freon production.

(B) Tetrachloroethene $(Cl_2C=CCl_2)$ is widely used as a solvent for dry cleaning.
Liquid carbon dioxide $(CO_2)$ is also used as an environmentally friendly solvent for dry cleaning.
Hydrogen peroxide $(H_2O_2)$ is used in the process of laundry for bleaching clothes to achieve better whiteness.
Acetaldehyde $(CH_3CHO)$ is not used as a dry cleaning agent.
Therefore,$a, b$ and $c$ are the chemicals used in the context of dry cleaning and laundry processes.