Chemical Properties of Carbon Compounds Questions in English

(D) When fuel does not burn completely,it produces soot (carbon particles) due to incomplete combustion. This soot deposits on the bottom of the cooking vessel,causing it to turn black.

(N/A) Most carbon compounds release a significant amount of heat and light when burned in air.
Saturated hydrocarbons burn with a clean flame and produce no smoke.
Carbon compounds used as fuels possess high calorific values,meaning they release a large amount of energy per unit mass.
Due to these properties,carbon and its compounds are widely used as fuels for most applications.

(N/A) Hydrogenation is the chemical process of adding hydrogen to a molecule. In organic chemistry,it typically involves the addition of hydrogen to unsaturated hydrocarbons (containing double or triple bonds) in the presence of catalysts like palladium $(Pd)$ or nickel $(Ni)$ to produce saturated hydrocarbons.
The general reaction is:
$R_2C=CR_2 + H_2 \xrightarrow{Ni \text{ catalyst}} R_2CH-CHR_2$
Its primary industrial application is the hydrogenation of vegetable oils. Vegetable oils contain long chains of unsaturated fatty acids. By hydrogenating these oils in the presence of a nickel catalyst,they are converted into saturated fats,which are solid at room temperature,commonly known as vanaspati ghee (hydrogenated vegetable fat).

(B) Addition reactions are characteristic of unsaturated hydrocarbons,which contain at least one double or triple bond between carbon atoms.
$1$. $C_{2}H_{6}$ (Ethane) and $C_{3}H_{8}$ (Propane) are alkanes (saturated hydrocarbons).
$2$. $CH_{4}$ (Methane) is an alkane (saturated hydrocarbon).
$3$. $C_{3}H_{6}$ (Propene) is an alkene (unsaturated hydrocarbon).
$4$. $C_{2}H_{2}$ (Ethyne) is an alkyne (unsaturated hydrocarbon).
Therefore,$C_{3}H_{6}$ and $C_{2}H_{2}$ undergo addition reactions.

(N/A) The bromine water test is commonly used to differentiate between saturated and unsaturated hydrocarbons.
When bromine water (a reddish-brown liquid) is added to an unsaturated hydrocarbon,the bromine reacts with the double or triple bonds,causing the reddish-brown color to disappear (decolorize).
In contrast,saturated hydrocarbons do not react with bromine water under normal conditions,so the reddish-brown color remains unchanged.

(A) Electrical wires are coated with insulating materials to prevent electric shocks and short circuits.
$PVC$ ($Polyvinyl$ $Chloride$) is a widely used plastic polymer that acts as an excellent electrical insulator.
Graphite is a conductor of electricity,and Sulphur is a brittle non-metal that does not possess the flexible,insulating properties required for wire coating.
Therefore,$PVC$ is the correct material used for this purpose.

(B) In the given reaction,ethanol $(CH_3-CH_2-OH)$ is converted into ethanoic acid $(CH_3-COOH)$.
This process involves the addition of oxygen to the alcohol group.
Alkaline $KMnO_4$ (Potassium permanganate) is a strong oxidizing agent that provides oxygen for this oxidation reaction.
Therefore,it acts as an oxidising agent.

(C) The process of converting unsaturated vegetable oils into saturated fats by reacting them with hydrogen in the presence of a catalyst like nickel $(Ni)$ or palladium $(Pd)$ is known as hydrogenation.
In this reaction,hydrogen atoms are added across the carbon-carbon double bonds $(C=C)$ of the unsaturated oil molecules to form single bonds $(C-C)$.
Since hydrogen is being added to the reactant to form a new product,this is classified as an addition reaction.

(A) Saturated hydrocarbons (alkanes) are generally unreactive in most conditions. However,they undergo substitution reactions with halogens like chlorine in the presence of sunlight (ultraviolet light).
This reaction is known as a free-radical substitution reaction.
For example,methane reacts with chlorine in the presence of sunlight to form chloromethane and hydrogen chloride: $CH_4 + Cl_2 \xrightarrow{sunlight} CH_3Cl + HCl$.

(N/A) Ethane $(C_2H_6)$ is a saturated hydrocarbon,while ethene $(C_2H_4)$ is an unsaturated hydrocarbon.
$1$. Bromine Water Test: When ethene is passed through bromine water (reddish-brown color),it reacts to form $1,2-$dibromoethane,causing the bromine water to decolorize. Ethane does not react with bromine water,so the color remains unchanged.
$2$. Baeyer's Test: Ethene reacts with alkaline $KMnO_4$ (purple color) to form ethylene glycol,causing the purple color to disappear. Ethane does not react with alkaline $KMnO_4$.

(N/A) The reaction used for the conversion of vegetable oils to fats is known as $Hydrogenation$.
$Hydrogenation$ is a chemical reaction in which hydrogen gas is added to unsaturated hydrocarbons (like vegetable oils containing double bonds) in the presence of a catalyst,such as $Nickel$ $(Ni)$,$Palladium$ $(Pd)$,or $Platinum$ $(Pt)$,to form saturated hydrocarbons (fats).
General reaction:
$R_2C=CR_2 + H_2 \xrightarrow{Ni \text{ catalyst}} R_2CH-CHR_2$
In this process,the $C=C$ double bond in the unsaturated oil molecule breaks,and two hydrogen atoms are added across the carbons,converting the liquid oil into a solid or semi-solid fat.

(N/A) This conversion is achieved by the dehydration of ethanol using hot concentrated $H_2SO_4$,which acts as a dehydrating agent.
Reaction: $CH_3CH_2OH \xrightarrow[conc. H_2SO_4]{Hot} CH_2=CH_2 + H_2O$
$(b)$ This conversion is achieved by the oxidation of propanol using an oxidizing agent such as alkaline $KMnO_4$ or acidified $K_2Cr_2O_7$.
Reaction: $CH_3CH_2CH_2OH \xrightarrow[Heat]{Alk. KMnO_4} CH_3CH_2COOH$

(N/A) Hydrogenation reaction: Unsaturated hydrocarbons add hydrogen in the presence of a nickel $(Ni)$ catalyst to form saturated hydrocarbons. Example: Ethene to Ethane.
$CH_2=CH_2 + H_2 \xrightarrow{Ni} CH_3-CH_3$
$(b)$ Oxidation reaction: Alcohols can be oxidized to carboxylic acids in the presence of oxidizing agents like alkaline potassium permanganate $(KMnO_4)$ or acidified potassium dichromate $(K_2Cr_2O_7)$ upon heating. Example: Ethanol to Ethanoic acid.
$CH_3CH_2OH \xrightarrow[Heat]{Alk. KMnO_4} CH_3COOH$
$(c)$ Substitution reaction: Saturated hydrocarbons are largely unreactive,but in the presence of sunlight $(hv)$,chlorine can replace hydrogen atoms one by one. Example: Methane to Chloromethane.
$CH_4 + Cl_2 \xrightarrow{hv} CH_3Cl + HCl$

(B) Unsaturated hydrocarbons (like alkenes and alkynes) have a higher percentage of carbon compared to saturated hydrocarbons.
When they burn in air,the oxygen available is often insufficient for complete combustion.
Due to the high carbon content,the carbon atoms do not get fully oxidized to $CO_2$,leading to the formation of unburnt carbon particles (soot).
These incandescent carbon particles glow with a yellow flame and are released as black smoke.

(N/A) Saturated hydrocarbons contain a lower percentage of carbon and have a higher hydrogen-to-carbon ratio, which allows for complete combustion in the presence of sufficient oxygen, resulting in a clean blue flame.
In contrast, unsaturated hydrocarbons have a higher percentage of carbon and a lower hydrogen-to-carbon ratio.
Due to this, they do not undergo complete combustion even in the presence of sufficient oxygen, leading to the formation of unburnt carbon particles.
These unburnt carbon particles glow and make the flame sooty or yellow.

(N/A) Hydrogenation is the chemical reaction involving the addition of hydrogen to unsaturated hydrocarbons (such as alkenes or alkynes) in the presence of a catalyst,such as palladium $(Pd)$,platinum $(Pt)$,or nickel $(Ni)$,to produce saturated hydrocarbons.
Example: $CH_2=CH_2$ (Ethene) $+ H_2 \xrightarrow{Ni} CH_3-CH_3$ (Ethane).
Industrial Application: This reaction is widely used in the food industry for the hydrogenation of liquid vegetable oils to produce solid fats like vanaspati ghee.

(N/A) $(i)$ Oxidation: Alcohols are converted into carboxylic acids in the presence of an oxidizing agent such as acidified $K_2Cr_2O_7$.
$CH_3CH_2OH \xrightarrow[Acidified]{K_2Cr_2O_7} CH_3COOH$
$(ii)$ Hydrogenation: Unsaturated hydrocarbons (like ethene) react with hydrogen in the presence of a catalyst like $Ni$ or $Pd$ to form saturated hydrocarbons.
$CH_2 = CH_2 + H_2 \xrightarrow[\Delta]{Ni} CH_3 - CH_3$
$(iii)$ Substitution: Saturated hydrocarbons (like methane) react with chlorine in the presence of sunlight to form chloroalkanes.
$CH_4 + Cl_2 \xrightarrow{Sunlight} CH_3Cl + HCl$

(A) The hydrocarbons in which an addition reaction with hydrogen is possible are known as $Alkene$s. Their general formula is $C_nH_{2n}$.
The essential condition for an addition reaction is the presence of a multiple bond (double or triple bond) between carbon atoms and the use of a catalyst such as $Ni$,$Pd$,or $Pt$.
Chemical equation (Hydrogenation of Ethene):
$CH_2=CH_2 + H_2 \xrightarrow{Ni/Pd/Pt} CH_3-CH_3$
Reactant: $Ethene$
Product: $Ethane$

(N/A) Vegetable oils generally contain unsaturated fatty acids,which are considered healthier for the human body compared to animal fats,which are rich in saturated fatty acids. Saturated fats are associated with higher risks of cardiovascular diseases.
The hydrogenation reaction of vegetable oils is represented as:
$R_2C = CR_2 + H_2 \xrightarrow{Ni/Pd/Pt} R_2CH - CR_2H$
The catalysts used in this reaction are typically finely divided $Ni$ (Nickel),$Pd$ (Palladium),or $Pt$ (Platinum).

(N/A) The conversion of $CH_{4}$ to $CCl_{4}$ occurs through the following successive steps in the presence of sunlight:
$1$. $CH_{4} + Cl_{2} \xrightarrow{\text{Sunlight}} CH_{3}Cl + HCl$
$2$. $CH_{3}Cl + Cl_{2} \xrightarrow{\text{Sunlight}} CH_{2}Cl_{2} + HCl$
$3$. $CH_{2}Cl_{2} + Cl_{2} \xrightarrow{\text{Sunlight}} CHCl_{3} + HCl$
$4$. $CHCl_{3} + Cl_{2} \xrightarrow{\text{Sunlight}} CCl_{4} + HCl$
This reaction is referred to as a substitution reaction because one or more hydrogen atoms of the hydrocarbon are replaced (substituted) by another atom or group of atoms (in this case,chlorine atoms).

(N/A) $(i)$ Vegetable oils contain unsaturated fatty acids,whereas vegetable ghee contains saturated fatty acids,which are considered harmful to health.
$(ii)$ Vegetable oils are converted into vegetable ghee by the addition of hydrogen in the presence of catalysts such as palladium $(Pd)$ or nickel $(Ni)$.
$(iii)$ The process involved is known as Hydrogenation (an addition reaction). It is defined as the chemical process of adding hydrogen atoms to the carbon-carbon double bonds of an organic compound to convert it into a saturated compound.

(A) is ethene $[CH_{2}=CH_{2}]$.
$B$ is ethane $[CH_{3}-CH_{3}]$.
$C$ is chloroethane $[CH_{3}-CH_{2}-Cl]$.
$(b)$ The chemical equation for the conversion of $A$ to $B$ is:
$CH_{2}=CH_{2} + H_{2} \xrightarrow{Ni/Pd/Pt} CH_{3}-CH_{3}$
Type of reaction: Hydrogenation (Addition reaction).

(N/A) Substances that are capable of adding oxygen to other substances or removing hydrogen from them are known as oxidising agents.
Two common examples of oxidising agents are:
$1$. Alkaline potassium permanganate $(KMnO_4)$
$2$. Acidified potassium dichromate $(K_2Cr_2O_7)$
Chemical equation for the oxidation of ethanol to ethanoic acid using an oxidising agent:
$CH_3CH_2OH \xrightarrow[\text{Acidified } K_2Cr_2O_7 + \text{Heat}]{\text{Alkaline } KMnO_4 + \text{Heat}} CH_3COOH$

(N/A) The given ester is pentyl ethanoate. It is prepared from ethanoic acid $(CH_3COOH)$ and pentan$-1-$ol $(CH_3CH_2CH_2CH_2CH_2OH)$.
The structural formula of ethanoic acid is:
$H-C(H)(H)-C(=O)-O-H$
The structural formula of pentan$-1-$ol is:
$H-C(H)(H)-C(H)(H)-C(H)(H)-C(H)(H)-C(H)(H)-O-H$
The process of formation of an ester from a carboxylic acid and an alcohol in the presence of an acid catalyst is called esterification.

(B) It is an unsaturated compound.
Reason: Unsaturated compounds have a higher percentage of carbon compared to saturated compounds.
Thus,unsaturated compounds undergo incomplete combustion in the presence of air,producing a yellow flame with a significant amount of black smoke (soot).

(B) When a fuel burns,it releases energy. If the supply of oxygen is insufficient,the combustion is incomplete. Incomplete combustion of hydrocarbons produces carbon particles (soot),which deposit on the bottom of the cooking vessel,causing it to turn black. Therefore,the blackening of the vessel indicates that the fuel is not burning completely.

(B) Carboxylic acids react with sodium bicarbonate $(NaHCO_3)$ to produce carbon dioxide $(CO_2)$ gas.
This reaction is characterized by the evolution of gas bubbles,known as effervescence.
The chemical equation for this reaction is: $RCOOH + NaHCO_3 \rightarrow RCOONa + H_2O + CO_2 \uparrow$.
This test is commonly used to distinguish carboxylic acids from other organic compounds like alcohols or aldehydes,which do not react with $NaHCO_3$ to release $CO_2$.

(C) Saturated hydrocarbons (alkanes) are generally unreactive towards many reagents.
However, they undergo a substitution reaction with chlorine in the presence of sunlight (ultraviolet light).
This reaction is known as a free-radical substitution reaction.
For example, methane reacts with chlorine in the presence of sunlight to form chloromethane and hydrogen chloride: $CH_4 + Cl_2 \xrightarrow{\text{sunlight}} CH_3Cl + HCl$.

(B) The statement is False.
Esters are typically formed by the process of esterification,which involves the reaction between a carboxylic acid and an alcohol in the presence of an acid catalyst (such as concentrated $H_2SO_4$).
Aldehydes and ketones do not react with each other to form esters.

(TRUE) The statement is True.
This reaction is known as saponification (when using a base) or acid-catalyzed hydrolysis.
$1$. In the presence of an acid,the reaction is a reversible hydrolysis where the ester reacts with water to form the corresponding carboxylic acid and alcohol.
$2$. In the presence of a base (like $NaOH$),the reaction is known as saponification,which is irreversible. The ester reacts with the base to form a carboxylate salt (soap) and alcohol. The carboxylic acid can then be obtained by acidifying the salt.

(B) The statement is False.
Carbon, in its various allotropic forms (such as diamond, graphite, or charcoal), burns in oxygen to produce carbon dioxide $(CO_2)$, not nitrogen dioxide $(NO_2)$.
The chemical reaction is: $C(s) + O_2(g) \rightarrow CO_2(g) + \text{Heat} + \text{Light}$.

(TRUE) The statement is $True$.
$1$. Saturated hydrocarbons (alkanes) contain a higher proportion of hydrogen relative to carbon,which allows for complete combustion in the presence of sufficient oxygen,resulting in a clean,blue flame.
$2$. Unsaturated hydrocarbons (alkenes and alkynes) have a higher percentage of carbon. Due to the incomplete combustion of these compounds,unburnt carbon particles are produced,which glow yellow and produce black smoke.

(FALSE) The statement is False.
Animal fats generally contain saturated fatty acids,which are associated with an increased risk of cardiovascular diseases and are considered less healthy compared to unsaturated fatty acids. Unsaturated fatty acids,typically found in vegetable oils,are generally considered better for heart health.

(D) Carbon is a non-metal.
$1$. Carbon reacts with $O_2$ (dioxygen) to form $CO_2$ or $CO$.
$2$. Carbon reacts with $H_2$ (dihydrogen) at high temperatures to form hydrocarbons like methane $(CH_4)$.
$3$. Carbon reacts with $Cl_2$ (dichlorine) to form carbon tetrachloride $(CCl_4)$.
$4$. Carbon does not react with dilute hydrochloric acid $(HCl)$ because it is a non-metal and cannot displace hydrogen from the acid.

(C) The process of converting vegetable oil into vegetable ghee (solid fat) is known as hydrogenation.
In this chemical reaction,hydrogen gas is added to unsaturated vegetable oils in the presence of a catalyst,typically $Nickel$ $(Ni)$,at a specific temperature.
The $Nickel$ catalyst facilitates the addition of hydrogen across the double bonds of the unsaturated fatty acids present in the oil,converting them into saturated fats,which are solid at room temperature.

(C) The process of converting vegetable oils (which contain unsaturated fatty acids) into vegetable ghee (which contains saturated fatty acids) is known as $Hydrogenation$.
In this process,vegetable oil is reacted with hydrogen gas in the presence of a catalyst,such as nickel $(Ni)$,at a specific temperature.
This addition of hydrogen across the double bonds of the unsaturated fats converts them into saturated fats,resulting in a solid or semi-solid state known as vegetable ghee.

(B) The process of converting vegetable oils into vegetable ghee (vanaspati ghee) is known as hydrogenation. In this process,unsaturated vegetable oils are reacted with $H_2$ (dihydrogen) gas in the presence of a catalyst,such as nickel $(Ni)$,at a specific temperature and pressure. This reaction converts the unsaturated fats into saturated fats,resulting in a solid or semi-solid state known as vegetable ghee.

(D) Para aminobenzoic acid $(PABA)$ is a chemical compound that can be synthesized using ammonia as a precursor in certain industrial chemical processes.
$PABA$ is used in the pharmaceutical industry for the production of various medicines,including local anesthetics like benzocaine and procaine.
While ammonium nitrate,diammonium phosphate,and ammonium sulphate are nitrogenous compounds,they are primarily used as fertilizers rather than as medicinal ingredients.

(C) The reduction of an aldehyde results in the formation of a primary alcohol.
Methanal $(HCHO)$ is the simplest aldehyde with one carbon atom.
When methanal undergoes reduction (addition of hydrogen),it is converted into methanol $(CH_{3}OH)$.
The chemical reaction is: $HCHO + 2[H] \rightarrow CH_{3}OH$.

(A) Propanone,commonly known as acetone,is a widely used organic solvent.
It is primarily used as a nail polish remover because it can dissolve various organic substances,including the polymers found in nail polish.
It is not used as an antiseptic,antibiotic,or preservative in common applications.

(C) Polythene is a polymer formed by the addition polymerization of ethene monomers.
In this process,many molecules of ethene $(CH_{2}=CH_{2})$ undergo a chemical reaction under high pressure and temperature in the presence of a catalyst to form a long-chain polymer known as polythene (polyethylene).
The chemical equation is: $n(CH_{2}=CH_{2}) \rightarrow -[CH_{2}-CH_{2}]_{n}-$.
Therefore,the correct monomer is ethene $(CH_{2}=CH_{2})$.

(C) The hydrolysis of sucrose (sugar or molasses) into glucose and fructose is catalyzed by the enzyme $Invertase$.
The chemical reaction is as follows:
$C_{12}H_{22}O_{11} (sucrose) + H_2O \xrightarrow{Invertase} C_6H_{12}O_6 (glucose) + C_6H_{12}O_6 (fructose)$.
$Zymase$ is the enzyme responsible for the further conversion of glucose and fructose into ethanol and carbon dioxide.

(B) Ethyl acetate is an ester formed by the reaction between acetic acid $(CH_{3}COOH)$ and ethanol $(C_{2}H_{5}OH)$.
In the esterification reaction,the hydroxyl group $(-OH)$ of the acid and the hydrogen atom of the alcohol's hydroxyl group are removed as water $(H_{2}O)$.
The remaining parts combine to form the ester: $CH_{3}COOH + C_{2}H_{5}OH \rightarrow CH_{3}COOC_{2}H_{5} + H_{2}O$.
Therefore,the molecular formula of ethyl acetate is $CH_{3}COOC_{2}H_{5}$.

(C) The oxidation of primary alcohols like methanol $(CH_{3}OH)$ in the presence of a mild oxidizing agent like $Ag_{2}O$ (silver oxide) at an appropriate temperature leads to the formation of an aldehyde.
Specifically, methanol is oxidized to form methanal $(HCHO)$, which is also known as formaldehyde.
The reaction can be represented as: $CH_{3}OH + [O] \xrightarrow{Ag_{2}O} HCHO + H_{2}O$.

(C) The oxidation of an aldehyde in the presence of an oxidising agent (like alkaline $KMnO_4$ or acidified $K_2Cr_2O_7$) results in the formation of a carboxylic acid with the same number of carbon atoms.
Methanal $(HCHO)$ is an aldehyde with one carbon atom.
Upon oxidation,it gets converted into methanoic acid $(HCOOH)$,which also contains one carbon atom.
The reaction is: $HCHO + [O] \xrightarrow{\text{oxidising agent}} HCOOH$.

(D) The Tollen's test,also known as the silver mirror test,is a chemical test used to distinguish between aldehydes and ketones.
Aldehydes contain the $-CHO$ functional group,which acts as a reducing agent.
When an aldehyde is treated with Tollen's reagent (ammoniacal silver nitrate),it reduces the silver ions $(Ag^+)$ to metallic silver $(Ag)$,which deposits on the inner walls of the test tube,forming a 'silver mirror'.
Ketones do not have the $-CHO$ group and therefore do not give a positive Tollen's test.

(A) The reduction of an aldehyde in the presence of a catalyst like palladium $(Pd)$ or nickel $(Ni)$ leads to the formation of a primary alcohol.
Methanal $(HCHO)$ is the simplest aldehyde.
When methanal undergoes catalytic hydrogenation (reduction),it reacts with hydrogen $(H_2)$ to form methanol $(CH_3OH)$.
The chemical equation is: $HCHO + H_2 \xrightarrow{Pd} CH_3OH$.

(C) The general formula for a ketone group is $R-CO-R'$,where $R$ and $R'$ are alkyl groups.
For the simplest ketone,the smallest possible alkyl groups are methyl groups $(-CH_3)$.
Therefore,the simplest ketone is $CH_3-CO-CH_3$,which is known as Propanone (also called Acetone).
Methanal and Ethanal are aldehydes,and Propenal is an unsaturated aldehyde.

(A) Propanone,commonly known as acetone,is a ketone with the chemical formula $C_{3}H_{6}O$.
Its structural formula is $CH_{3}-CO-CH_{3}$,which indicates a central carbonyl group $(C=O)$ bonded to two methyl groups $(CH_{3})$.
Therefore,the correct molecular formula is $CH_{3}COCH_{3}$.

(D) The liquid used to remove nail polish is commonly known as a nail polish remover. The primary active ingredient in most nail polish removers is $Acetone$ $(CH_3COCH_3)$. $Acetone$ is a simple ketone that acts as a powerful solvent,effectively dissolving the polymers and resins present in the nail polish,allowing it to be wiped away easily.