Mix Examples - Carbon and its Compounds Questions in English

(N/A) The element is Carbon $(C)$.
$(b)$ The oxide of carbon is Carbon dioxide $(CO_2)$. The electron dot structure involves carbon sharing two pairs of electrons with each of the two oxygen atoms to complete its octet.
$(c)$ Methane $(CH_4)$ has one carbon atom bonded to four hydrogen atoms. Ethane $(C_2H_6)$ has two carbon atoms bonded to each other and to three hydrogen atoms each.

(A) Two properties of carbon that make it unique among other elements are:
$(i)$ Catenation: Carbon has the unique ability to form strong covalent bonds with other carbon atoms,resulting in the formation of long chains,branched chains,or ring structures.
$(ii)$ Tetravalency: Carbon has a valency of $4$,allowing it to form stable bonds with four other atoms of carbon or other monovalent elements like hydrogen,oxygen,nitrogen,or halogens.
Two uses of carbon based on its properties are:
$(i)$ Graphite (an allotrope of carbon) is used in pencil leads and as a dry lubricant due to its layered structure and weak inter-layer forces.
$(ii)$ Diamond (an allotrope of carbon) is used in cutting and drilling tools because of its extremely hard,three-dimensional tetrahedral crystal lattice structure.

(N/A) $(i)$ Reaction with Sodium:
$2CH_{3}COOH + 2Na \longrightarrow 2CH_{3}COONa + H_{2}$
Main product: Sodium ethanoate.
$(ii)$ Reaction with Sodium hydroxide:
$CH_{3}COOH + NaOH \longrightarrow CH_{3}COONa + H_{2}O$
Main product: Sodium ethanoate.
$(iii)$ Reaction with Ethanol:
$CH_{3}COOH + C_{2}H_{5}OH \xrightarrow{acid} CH_{3}COOC_{2}H_{5} + H_{2}O$
Main product: Ethyl ethanoate (ester).

(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:
$CH_3CH_2OH \xrightarrow[\text{Acidified } K_2Cr_2O_7 + \text{Heat}]{\text{Alkaline } KMnO_4 + \text{Heat}} CH_3COOH$

(A) $(i)$ The hydrocarbon is Ethene.
$(ii)$ It belongs to the Alkene family.
$(iii)$ The reaction of Ethene with Hydrogen in the presence of a catalyst (like Nickel or Palladium) results in the formation of Ethane:
$C_{2}H_{4} + H_{2} \xrightarrow{Ni/Pd} C_{2}H_{6}$

(N/A) $(i)$ Covalent compounds have low melting and boiling points because the intermolecular forces between them are weak.
$(ii)$ Generally,these are poor conductors of electricity because the electrons are shared between atoms and no free charged particles (ions) are formed.
$(iii)$ Generally,covalent compounds are soluble in organic solvents,such as ether or benzene,and are insoluble in water. This is because these compounds are typically non-polar and follow the principle of 'like dissolves like',meaning they dissolve in non-polar solvents.

(A) $(i)$ $'A'$ is Ethanol $(CH_{3}CH_{2}OH)$ and $'B'$ is Ethanoic acid $(CH_{3}COOH)$.
$(ii)$ The reaction of Ethanoic acid with baking soda $(NaHCO_{3})$ is:
$CH_{3}COOH + NaHCO_{3} \longrightarrow CH_{3}COONa + CO_{2} \uparrow + H_{2}O$
This reaction releases carbon dioxide gas,which causes the observed effervescence.

(N/A) $(i)$ The element is Oxygen $(O)$.
$(ii)$ The bond formation between two oxygen atoms is shown in the figure.
$(iii)$ The nature of the bond is a double covalent bond,as each oxygen atom shares two electrons to complete its octet.

(N/A) For the molecular formula $C_{3}H_{6}O$,the two isomers are:
$1$. Propanal (Aldehyde): The structure is $CH_{3}-CH_{2}-CHO$.
$2$. Propanone (Ketone): The structure is $CH_{3}-CO-CH_{3}$.
Relation: These two compounds are functional isomers because they possess the same molecular formula but contain different functional groups (aldehyde group $-CHO$ and ketone group $>C=O$).

(N/A) $(i)$ Ethanol test (Reaction with Sodium metal):
Ethanol reacts with sodium metal to evolve hydrogen gas,which can be tested by bringing a burning splinter near the gas,producing a 'pop' sound.
$2 CH_3CH_2OH + 2 Na \rightarrow 2 CH_3CH_2ONa + H_2 \uparrow$
$(ii)$ Ethanoic acid test (Esterification reaction):
Ethanoic acid reacts with ethanol in the presence of an acid catalyst to form an ester,which has a sweet,fruity smell.
$CH_3COOH + CH_3CH_2OH \xrightarrow{H^+} CH_3COOCH_2CH_3 + H_2O$
$(b)$ Pure ethanoic acid has a melting point of $290 \, K$. In cold climates,it often freezes into an ice-like solid during winter,which is why it is known as glacial acetic acid.

(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.

(N/A) covalent bond is formed when two atoms share valence electrons to achieve a stable noble gas electronic configuration,as they cannot gain or lose electrons from their outermost shell.
Physical properties of covalent compounds include:
$(i)$ They are generally poor conductors of electricity.
$(ii)$ They have low boiling and melting points due to weak intermolecular forces.
$(iii)$ They are generally soluble in organic solvents.
$(iv)$ They are typically found in liquid or gaseous states at room temperature.
In $CCl_{4}$,carbon has $4$ valence electrons and each of the four chlorine atoms has $7$ valence electrons. Carbon shares one electron with each of the four chlorine atoms to complete its octet,and each chlorine atom completes its octet by sharing one electron with carbon.

(N/A) Butanol.
$(b)$ Pentanoic acid.
$(c)$ Propan-$2$-one. An atom or group of atoms attached to the carbon chain by replacing one or more hydrogen atoms,which acts as a reactive site in the molecule and decides the chemical properties of the compound,is called a functional group.

Functional Group	Formula and Example
$1.$ Aldehyde	Formula: $-CHO$,Example: Ethanal $(CH_3CHO)$
$2.$ Ketone	Formula: $>C=O$,Example: Propanone $(CH_3COCH_3)$
$3.$ Carboxylic acid	Formula: $-COOH$,Example: Ethanoic acid $(CH_3COOH)$

(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).

(N/A) Hard water contains dissolved salts of calcium and magnesium,specifically their bicarbonates,chlorides,and sulphates. When soap (which consists of sodium or potassium salts of long-chain fatty acids) is added to hard water,these calcium and magnesium ions react with the soap molecules to form insoluble precipitates known as scum. Because the soap molecules are consumed in this chemical reaction to form scum,they are no longer available to form micelles and perform the cleansing action on clothes.

(D) The molecular formula of ethane is $C_{2}H_{6}$.
In ethane,there are two carbon atoms linked by a single covalent bond $(C-C)$.
Each carbon atom is further bonded to three hydrogen atoms by single covalent bonds $(C-H)$.
Total bonds = $1$ ($C-C$ bond) + $6$ ($C-H$ bonds) = $7$ covalent bonds.
Therefore,ethane has $7$ covalent bonds.

(A) Butanone has the chemical formula $CH_3COCH_2CH_3$.
The suffix '-one' in the $IUPAC$ name indicates the presence of a ketone functional group $(>C=O)$.
In butanone,the carbonyl group is attached to two carbon atoms,which is the characteristic structure of a ketone.

(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.

(C) Alcohols are organic compounds containing a hydroxyl $(-OH)$ functional group attached to a saturated carbon atom.
The general formula for an alkane is $C_{n}H_{2n+2}$.
When one hydrogen atom is replaced by an $-OH$ group,the alkyl group becomes $C_{n}H_{2n+1}$.
Therefore,the general formula for a monohydric alcohol is $C_{n}H_{2n+1}-OH$.

(D) The conversion of ethanol $(CH_3CH_2OH)$ to ethanoic acid $(CH_3COOH)$ involves the addition of oxygen or the removal of hydrogen.
This chemical process is known as oxidation.
In the presence of oxidizing agents like alkaline potassium permanganate $(KMnO_4)$ or acidified potassium dichromate $(K_2Cr_2O_7)$, ethanol is oxidized to ethanoic acid.
The reaction is: $CH_3CH_2OH + 2[O] \xrightarrow{alkaline KMnO_4/heat} CH_3COOH + H_2O$.

(A) Alkynes are unsaturated hydrocarbons that contain at least one carbon-carbon triple bond.
The general formula for alkanes is $C_{n}H_{2n+2}$.
The general formula for alkenes is $C_{n}H_{2n}$.
The general formula for alkynes is $C_{n}H_{2n-2}$,where $n$ is the number of carbon atoms $(n \ge 2)$.

(B) triple bond is formed when two atoms share three pairs of electrons between them.
In a triple bond,each carbon atom contributes three electrons to the shared pool,resulting in a total of $3$ shared electron pairs.
Therefore,the number of electron pairs shared by two carbon atoms bonded by a triple bond is $3$ pairs.

(C) Ethanol $(CH_{3}CH_{2}OH)$ can be oxidised to ethanoic acid $(CH_{3}COOH)$ using strong oxidising agents.
Alkaline potassium permanganate $(KMnO_{4})$ is a common oxidising agent used in laboratory settings to convert alcohols into carboxylic acids.
While acidic potassium dichromate $(K_{2}Cr_{2}O_{7})$ is also a strong oxidising agent,the question specifically asks for an alkaline agent,making alkaline $KMnO_{4}$ the correct choice.

(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) The atomic number of nitrogen $(N)$ is $7$. Its electronic configuration is $2, 5$.
To achieve a stable octet,each nitrogen atom needs $3$ more electrons.
Therefore,two nitrogen atoms share $3$ pairs of electrons between them to form a triple covalent bond.
Each nitrogen atom has one lone pair of electrons remaining.
The correct electron dot structure is represented by showing $3$ shared pairs of electrons between the two $N$ atoms and one lone pair on each $N$ atom,which is $:N \vdots N:$. Among the given options,the structure representing $3$ shared pairs (triple bond) and one lone pair on each atom is correctly depicted in option $C$.

(B) Ethyne,also known as acetylene,has the chemical formula $C_{2}H_{2}$.
It consists of two carbon atoms connected by a triple bond,with each carbon atom also bonded to a single hydrogen atom.
The structural formula is $H - C \equiv C - H$.
Option $B$ correctly represents this structure.

(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: $CH_4 + Cl_2 \xrightarrow{\text{sunlight}} CH_3Cl + HCl$.

(D) Carbon has an atomic number of $6$. Its electronic configuration is $2, 4$.
To achieve a stable octet,carbon shares its $4$ valence electrons with other atoms to form $4$ covalent bonds.
By sharing $4$ electrons,carbon gains $4$ additional electrons in its valence shell,resulting in a total of $8$ valence electrons ($2 + 4 + 4 = 10$ total electrons).
The electronic configuration becomes $2, 8$,which is the configuration of the noble gas neon ($Ne$,atomic number $10$).

(A) water molecule $(H_2O)$ consists of one oxygen atom bonded to two hydrogen atoms.
Oxygen has $6$ valence electrons and requires $2$ more to complete its octet.
Each hydrogen atom has $1$ valence electron and requires $1$ more to complete its duplet.
Oxygen shares one electron with each hydrogen atom,forming two covalent bonds.
This leaves two lone pairs of electrons on the oxygen atom.
The correct electron dot structure represents the shared pairs as colons $(:)$ and shows the lone pairs on the oxygen atom as two pairs of dots.
Thus,the structure is $H:\underset{\centerdot \,\centerdot }{\overset{\centerdot \,\centerdot }{\mathop{O}}}\,:H$.

(A) straight chain hydrocarbon is one where carbon atoms are linked in a single continuous chain without any branching.
Option $A$ represents a branched structure ($2$-methylpentane).
Option $B$ represents a branched structure ($2$-methylpentane).
Option $C$ represents a branched structure ($3$-methylhexane).
Option $D$ represents a straight chain hydrocarbon (n-pentane).
Since the question asks for the structure that is $NOT$ a straight chain,and options $A, B,$ and $C$ are all branched,the question implies identifying the branched ones. However,based on standard chemistry nomenclature,$D$ is the only straight chain. If the question asks which is $NOT$ straight,$A, B,$ and $C$ are correct. Given the typical format of such questions,$A$ is a clear example of a branched chain.

(C) Unsaturated hydrocarbons are those that contain at least one carbon-carbon double bond $(C=C)$ or triple bond $(C\equiv C)$.
$(i)$ $H_3C-CH_2-CH_2-CH_3$ is Butane,which is a saturated hydrocarbon (alkane).
$(ii)$ $H_3C-C\equiv C-CH_3$ is But$-2-$yne,which contains a triple bond,so it is unsaturated.
$(iii)$ $H_3C-CH(CH_3)-CH_3$ is Isobutane ($2$-methylpropane),which is a saturated hydrocarbon (alkane).
$(iv)$ $H_3C-C(CH_3)=CH_2$ is $2-$methylpropene,which contains a double bond,so it is unsaturated.
Therefore,$(ii)$ and $(iv)$ are unsaturated hydrocarbons.

(D) The molecular formula of pentane is $C_{5}H_{12}$.
To find the number of covalent bonds,we can use the structural formula of pentane.
Pentane is an alkane with a straight chain of $5$ carbon atoms.
Each carbon atom is bonded to other atoms via single covalent bonds.
There are $4$ $C-C$ bonds between the $5$ carbon atoms.
Each carbon atom is also bonded to hydrogen atoms to satisfy its valency of $4$.
Specifically,the $3$ terminal carbon atoms are bonded to $3$ hydrogen atoms each ($3 \times 3 = 9$ bonds),and the $2$ internal carbon atoms are bonded to $2$ hydrogen atoms each ($2 \times 2 = 4$ bonds). However,in a chain of $5$ carbons $(C-C-C-C-C)$,there are $4$ $C-C$ bonds and $12$ $C-H$ bonds.
Total covalent bonds = (Number of $C-C$ bonds) + (Number of $C-H$ bonds) = $4 + 12 = 16$ covalent bonds.
Alternatively,for any alkane with $n$ carbon atoms,the total number of covalent bonds is given by the formula $3n + 1$.
For pentane,$n = 5$,so total bonds = $3(5) + 1 = 15 + 1 = 16$.

(A) When ethanol $(C_2H_5OH)$ reacts with sodium metal $(Na)$,it undergoes a substitution reaction where the hydrogen atom of the hydroxyl group is replaced by sodium.
This reaction produces sodium ethoxide $(C_2H_5ONa)$ and releases hydrogen gas $(H_2)$.
The balanced chemical equation is: $2C_2H_5OH + 2Na \rightarrow 2C_2H_5ONa + H_2 \uparrow$.

(B) Vinegar is a common household substance used as a preservative and flavoring agent.
It is chemically defined as a dilute solution of acetic acid $(CH_3COOH)$.
Specifically,vinegar typically contains $5 \%-8 \%$ acetic acid dissolved in water.
Therefore,the correct option is $B$.

(C) homologous series is a group of organic compounds having the same functional group and similar chemical properties,where each successive member differs by a $CH_{2}$ unit.
For alkanes,the general formula is $C_{n}H_{2n+2}$.
$CH_{4}$ $(n=1)$ follows $C_{n}H_{2n+2}$.
$C_{2}H_{6}$ $(n=2)$ follows $C_{n}H_{2n+2}$.
$C_{3}H_{8}$ $(n=3)$ follows $C_{n}H_{2n+2}$.
$C_{4}H_{8}$ follows the general formula $C_{n}H_{2n}$,which represents an alkene.
Therefore,$C_{4}H_{8}$ belongs to a different homologous series.

(D) The given compound is $CH_{3}-CH_{2}-CHO$.
This compound contains a chain of $3$ carbon atoms.
The functional group present is the aldehyde group $(-CHO)$.
For a $3$-carbon chain,the prefix is 'prop-'.
Since it is an aldehyde,the suffix '-al' is added to the alkane name.
Therefore,the $IUPAC$ name is Propanal.

(A) In organic chemistry,a heteroatom is any atom other than carbon or hydrogen present in an organic molecule.
The given molecule is $CH_{3}-CH_{2}-O-CH_{2}-CH_{2}Cl$.
$1$. Carbon $(C)$ and Hydrogen $(H)$ are the basic elements of the organic backbone.
$2$. Oxygen $(O)$ is a heteroatom because it is not carbon or hydrogen.
$3$. Chlorine $(Cl)$ is a heteroatom because it is not carbon or hydrogen.
Therefore,the heteroatoms present are oxygen $(i)$ and chlorine $(iv)$.

(B) The general formula for the alkyne homologous series is $C_nH_{2n-2}$,where $n$ represents the number of carbon atoms.
For the first member,we set $n = 2$ because a triple bond requires at least two carbon atoms.
Substituting $n = 2$ into the formula: $C_2H_{2(2)-2} = C_2H_{4-2} = C_2H_2$.
This compound is known as ethyne (also called acetylene).
Therefore,the first member of the alkyne series is ethyne.

(TRUE) The statement is True.
Soap consists of sodium or potassium salts of long-chain fatty acids.
When soap is added to hard water,which contains dissolved calcium $(Ca^{2+})$ and magnesium $(Mg^{2+})$ ions,these ions react with the soap molecules.
This reaction leads to the formation of an insoluble precipitate known as scum (or curd),which makes it difficult for soap to form a lather.

(FALSE) The statement is False.
When alcohols (such as ethanol) react with sodium metal,they produce sodium alkoxide and hydrogen gas $(H_2)$,not carbon dioxide $(CO_2)$.
The chemical equation for the reaction is:
$2CH_3CH_2OH + 2Na \rightarrow 2CH_3CH_2ONa + H_2 \uparrow$

(A) The statement is True.
When ethanol $(CH_3CH_2OH)$ is heated with excess concentrated sulphuric acid $(H_2SO_4)$ at $443 \,K$,it undergoes dehydration.
The concentrated sulphuric acid acts as a dehydrating agent,removing a water molecule from the ethanol.
The chemical reaction is: $CH_3CH_2OH \xrightarrow[443 \,K]{Conc. H_2SO_4} CH_2=CH_2 + H_2O$ (ethene).

(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.

(FALSE) False. $A$ nitrogen molecule $(N_2)$ is formed by the sharing of three pairs of electrons between two nitrogen atoms,resulting in a triple covalent bond $(N \equiv N)$.

(TRUE) True. Ethanoic acid $(CH_3COOH)$ is a weak organic acid. When it reacts with a strong base like sodium hydroxide $(NaOH)$,it undergoes a neutralization reaction to form sodium ethanoate $(CH_3COONa)$ and water $(H_2O)$. The chemical equation is: $CH_3COOH + NaOH \rightarrow CH_3COONa + H_2O$.

(B) The functional group $(-CHO)$ is known as the aldehyde group.
Compounds containing this group are classified as aldehydes.
Amides contain the $(-CONH_2)$ group,ketones contain the $(>C=O)$ group,and alcohols contain the $(-OH)$ group.

(B) The functional group present in carboxylic acid is the carboxyl group,which is represented by the formula $-COOH$.
In this group,a carbon atom is double-bonded to an oxygen atom and single-bonded to a hydroxyl group $(-OH)$.