Mix Examples - Carbon and its Compounds Questions in English

(A) Carbon is present in the Earth's atmosphere primarily as $CO_2$ (carbon dioxide).
While $CO_2$ is the most abundant form,carbon monoxide $(CO)$ is also present in the atmosphere in trace amounts due to incomplete combustion of fossil fuels and other natural processes.
Therefore,carbon exists in the atmosphere in the form of carbon monoxide in traces and carbon dioxide.

(B) Carbon compounds are covalent compounds formed by the sharing of electrons.
$(i)$ They do not contain charged particles (ions) and are therefore poor conductors of electricity. Thus,statement $(ii)$ is correct and $(i)$ is incorrect.
$(ii)$ Due to the covalent nature of the bonds,the forces of attraction between the molecules are not very strong. Consequently,they have low melting and boiling points. Thus,statement $(iv)$ is correct and $(iii)$ is incorrect.
Therefore,statements $(ii)$ and $(iv)$ are correct.

(C) In an ammonia molecule $(NH_3)$,the central nitrogen atom $(N)$ has $5$ valence electrons.
It forms three covalent bonds with three hydrogen atoms $(H)$ to complete its octet.
Each $N-H$ bond is a single covalent bond formed by the sharing of one pair of electrons.
Therefore,the ammonia molecule contains only three single bonds and one lone pair of electrons on the nitrogen atom.

(D) Buckminsterfullerene is a spherical molecule with the formula $C_{60}$.
It is one of the well-known allotropes of carbon,consisting of $60$ carbon atoms arranged in a structure resembling a soccer ball (a truncated icosahedron).
Other common allotropes of carbon include diamond and graphite.

(A) Butane has the molecular formula $C_4H_{10}$.
Structural isomers are compounds with the same molecular formula but different structural arrangements.
$(i)$ $n$-butane is a straight-chain isomer of butane $(C_4H_{10})$.
(ii) Isobutane ($2$-methylpropane) is a branched-chain isomer of butane $(C_4H_{10})$.
(iii) Cyclobutane has the formula $C_4H_8$,so it is not an isomer of butane.
(iv) The structure shown is not a valid isomer of butane.
Therefore,$(i)$ and $(ii)$ are the correct structural isomers of butane.

(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.

(D) The functional group $-OH$ represents an alcohol.
In the given options:
$1$. Butanone is a ketone with the functional group $C=O$.
$2$. Butanal is an aldehyde with the functional group $-CHO$.
$3$. Butanoic acid is a carboxylic acid with the functional group $-COOH$.
$4$. Butanol is an alcohol with the functional group $-OH$.
Therefore,the correct option is $D$.

(A) soap molecule consists of two parts: a long hydrocarbon chain and an ionic end.
$1$. The ionic end is hydrophilic,meaning it is water-attracting (water-loving).
$2$. The long hydrocarbon chain is hydrophobic,meaning it is water-repelling (water-fearing).
Therefore,the soap molecule has a hydrophilic head and a hydrophobic tail.

(B) The atomic number of nitrogen $(N)$ is $7$,and 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.
In the electron dot structure,the $3$ shared pairs are represented by $3$ dots between the two $N$ atoms,and the remaining lone pair on each nitrogen is represented by $2$ dots.
Thus,the correct representation is $:N \vdots N:$.

(C) Ethyne,also known as acetylene,is the simplest alkyne with the chemical formula $C_2H_2$.
It consists of two carbon atoms connected by a triple bond,with each carbon atom bonded to one hydrogen atom.
The structural formula is represented as $H-C\equiv C-H$.

(D) Unsaturated compounds are those hydrocarbons that contain at least one carbon-carbon double bond $(C=C)$ or triple bond $(C≡C)$.
$(i)$ Propane $(C_3H_8)$ is an alkane,which is a saturated hydrocarbon.
$(ii)$ Propene $(C_3H_6)$ contains a double bond,making it an unsaturated hydrocarbon.
$(iii)$ Propyne $(C_3H_4)$ contains a triple bond,making it an unsaturated hydrocarbon.
$(iv)$ Chloropropane $(C_3H_7Cl)$ is a substituted alkane,which is saturated.
Therefore,$(ii)$ and $(iii)$ are unsaturated compounds.

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

(B) Soap molecules are sodium or potassium salts of long-chain carboxylic acids.
Each soap molecule has two parts: a long hydrocarbon chain (hydrophobic tail) and an ionic head (hydrophilic head).
When soap is dissolved in water,the hydrophobic tails cluster together to avoid contact with water,forming the interior of the micelle.
The hydrophilic ionic heads face outward towards the water,forming the surface of the micelle.
Therefore,the ionic end is on the surface,and the carbon chain is in the interior of the cluster.

(C) The molecular formula of pentane is $C_5H_{12}$.
In pentane,there are $5$ carbon atoms linked together in a chain by $4$ $C-C$ single covalent bonds.
Each carbon atom is bonded to hydrogen atoms to satisfy its valency of $4$.
There are $12$ $C-H$ single covalent bonds.
Total number of covalent bonds = (Number of $C-C$ bonds) + (Number of $C-H$ bonds) = $4 + 12 = 16$ covalent bonds.

(D) Benzene $(C_6H_6)$ is an aromatic hydrocarbon with a cyclic structure.
It consists of a six-carbon ring with alternating single and double bonds.
Each carbon atom in the ring is bonded to one hydrogen atom.
Option $D$ correctly represents this structure,showing the alternating double bonds and the correct valency for each carbon atom.

(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.
The chemical equation for this reaction is:
$2C_2H_5OH + 2Na \rightarrow 2C_2H_5ONa + H_2 \uparrow$
In this reaction,$C_2H_5ONa$ (sodium ethoxide) and $H_2$ (hydrogen gas) are formed.
Therefore,the correct products are sodium ethoxide and hydrogen.

(B) Butanoic acid is a carboxylic acid with a four-carbon chain. The general formula for a carboxylic acid is $R-COOH$. For butanoic acid,the chain length is $n=4$. The structure is $CH_3-CH_2-CH_2-COOH$. Option $B$ correctly represents this structure,where the carbon atoms are bonded in a linear chain and the terminal carbon is part of the carboxyl group $(-COOH)$.

(C) Vinegar is a common household substance used for cooking and preservation.
It is chemically defined as a dilute solution of acetic acid $(CH_3COOH)$.
The standard concentration of acetic acid in vinegar typically ranges from $5 \%$ to $8 \%$ by volume.
The solvent used in this solution is water.
Therefore,vinegar is a $5 \%-8 \%$ solution of acetic acid in water.

(D) Mineral acids (such as $HCl$,$H_2SO_4$,$HNO_3$) are strong acids because they dissociate completely into ions in an aqueous solution.
Carboxylic acids (such as $CH_3COOH$) are weak acids because they dissociate only partially into ions in an aqueous solution.
Therefore,statement $(i)$ (mineral acids are completely ionised) and statement $(iv)$ (carboxylic acids are partially ionised) correctly explain why mineral acids are stronger than carboxylic acids.
Thus,the correct option is $(i)$ and $(iv)$.

(A) 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,making the total number of electrons in the valence shell $4 + 4 = 8$.
This results in a total of $2 + 8 = 10$ electrons,which corresponds to the electronic configuration of neon ($10$ electrons: $2, 8$).

(C) straight chain hydrocarbon is one where carbon atoms are linked in a single continuous line without any side chains or branches.
Option $B$ represents $n$-hexane,which is a straight chain.
Option $A$ is $CH_3-CH_2-CH_2-CH_2-CH_2-CH_3$,which is $n$-hexane (straight chain).
Option $C$ is $2$-methylpentane,which has a methyl group attached to the second carbon,making it a branched chain hydrocarbon.
Option $D$ is also a representation of a straight chain hydrocarbon.
Therefore,option $C$ is the correct answer as it is a branched chain hydrocarbon.

(D) 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,a saturated hydrocarbon (alkane).
$(ii) H_3C - C \equiv C - CH_3$ is But$-2-$yne,which contains a carbon-carbon triple bond,making it unsaturated.
$(iii) H_3C - CH(CH_3) - CH_3$ is Isobutane ($2$-methylpropane),a saturated hydrocarbon (alkane).
$(iv) H_3C - C(CH_3) = CH_2$ is $2-$methylpropene,which contains a carbon-carbon double bond,making it unsaturated.
Therefore,$(ii)$ and $(iv)$ are unsaturated hydrocarbons.

(A) 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.
Compounds with the general formula $C_nH_{2n+2}$ belong to the alkane series.
Checking the given options:
$B) C_2H_6$ follows $C_nH_{2n+2}$ ($n=2$,$2(2)+2=6$).
$C) C_3H_8$ follows $C_nH_{2n+2}$ ($n=3$,$2(3)+2=8$).
$D) CH_4$ follows $C_nH_{2n+2}$ ($n=1$,$2(1)+2=4$).
$A) C_4H_8$ follows the general formula $C_nH_{2n}$,which represents the alkene series.
Therefore,$C_4H_8$ does not belong to the same homologous series as the others.

(B) The given compound is $CH_{3}-CH_{2}-CHO$.
This molecule contains a chain of $3$ carbon atoms.
The functional group present is the aldehyde group $(-CHO)$.
For an aldehyde with $3$ carbon atoms,the parent alkane is propane.
Replacing the terminal '$e$' of propane with '$al$' gives the name propanal.
Therefore,the correct name is propanal.

(C) In organic chemistry,atoms other than carbon and hydrogen present in a molecule are known as heteroatoms.
In the given compound $CH_{3}-CH_{2}-O-CH_{2}-CH_{2}Cl$:
$1$. Carbon $(C)$ and Hydrogen $(H)$ are the basic elements forming the hydrocarbon chain.
$2$. Oxygen $(O)$ and Chlorine $(Cl)$ are atoms other than carbon and hydrogen.
Therefore,Oxygen and Chlorine are the heteroatoms present in the molecule.
Thus,the correct option is $(i)$ and $(iv)$.

(D) Saponification is the process of alkaline hydrolysis of an ester to produce a soap (carboxylate salt) and an alcohol.
In this reaction,an ester $(CH_3COOC_2H_5)$ reacts with a strong base $(NaOH)$ to form sodium acetate $(CH_3COONa)$ and ethanol $(C_2H_5OH)$.
Option $D$ correctly represents this reaction: $CH_3COOC_2H_5 + NaOH \rightarrow CH_3COONa + C_2H_5OH$.

(A) The general formula for the alkyne homologous series is $C_nH_{2n-2}$,where $n$ is 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: $C_2H_{2(2)-2} = C_2H_2$.
$C_2H_2$ is known as ethyne (also called acetylene).
Therefore,the first member of the alkyne series is ethyne.

(N/A) The chemical formula of ethyne is $C_2H_2$.
In ethyne, there is a triple bond between the two carbon atoms and a single bond between each carbon atom and a hydrogen atom.
Electron dot structure: $H : C \vdots \vdots C : H$
Structural formula: $H - C \equiv C - H$

(C) The compound $CH_3-CH_2-CH_2-CH_2-COOH$ contains $5$ carbon atoms in the main chain and a carboxylic acid functional group $(-COOH)$. Therefore,its $IUPAC$ name is Pentanoic acid.
$(b)$ The compound $CH_3-CH_2-C \equiv CH$ contains $4$ carbon atoms in the main chain and a triple bond between the $3^{rd}$ and $4^{th}$ carbon atoms. Therefore,its $IUPAC$ name is But$-1-$yne or simply Butyne.

(D) The given structure is $CH_3-CH_2-CH_2-CH_2-CH_2-CH_2-CHO$. It contains $7$ carbon atoms and an aldehyde functional group $(-CHO)$. Therefore,the $IUPAC$ name is Heptanal.
$(b)$ The given structure is $CH_3-CH_2-CH_2-CH_2-CH_2-OH$. It contains $5$ carbon atoms and an alcohol functional group $(-OH)$. Therefore,the $IUPAC$ name is Pentanol.

(A) The structure $CH_3-CH_2-CH_2-OH$ contains the $-OH$ group,which is the functional group for alcohols. Therefore,it is an alcohol (propanol).
$(b)$ The structure $CH_3-CH_2-COOH$ contains the $-COOH$ group,which is the functional group for carboxylic acids. Therefore,it is a carboxylic acid (propanoic acid).

(A) The structure $CH_3-CO-CH_2-CH_3$ contains a carbonyl group bonded to two carbon atoms,which is characteristic of a $\text{Ketone}$ functional group.
$(b)$ The structure $CH_3-CH_2-CH=CH_2$ contains a carbon-carbon double bond,which is characteristic of an $\text{Alkene}$ functional group.

(A) The carboxylic acid is ethanoic acid $(CH_{3}COOH)$.
$(b)$ The alcohol is ethanol $(C_{2}H_{5}OH)$.
$(c)$ The compound $X$ is ethyl ethanoate $(CH_{3}COOC_{2}H_{5})$.
The reaction is an esterification reaction:
$CH_{3}COOH + C_{2}H_{5}OH \xrightarrow{H_{2}SO_{4}} CH_{3}COOC_{2}H_{5} + H_{2}O$

(B) Detergents are considered better cleansing agents than soaps because they can function effectively in both hard and soft water.
Soaps react with calcium $(Ca^{2+})$ and magnesium $(Mg^{2+})$ ions present in hard water to form insoluble precipitates known as scum,which reduces their cleaning efficiency.
In contrast,the charged ends of detergent molecules do not form insoluble precipitates with these ions,allowing them to maintain their cleansing action even in hard water.

(A) $(a) CH_3COCH_2CH_2CH_2CH_3$ contains a ketone group $(-CO-)$.
$(b) CH_3CH_2CH_2COOH$ contains a carboxylic acid group $(-COOH)$.
$(c) CH_3CH_2CH_2CH_2CHO$ contains an aldehyde group $(-CHO)$.
$(d) CH_3CH_2OH$ contains an alcohol group $(-OH)$.

(N/A) Ethanol,when heated with excess concentrated sulphuric acid $(H_{2}SO_{4})$ at $443\, K$,undergoes dehydration to produce ethene.
The chemical reaction is as follows:
$CH_{3}CH_{2}OH \xrightarrow[443\, K]{\text{Hot conc. } H_{2}SO_{4}} CH_{2}=CH_{2} + H_{2}O$

(N/A) Methanol is oxidized to methanal in the liver.
Methanal reacts rapidly with the components of cells.
It causes the protoplasm to coagulate.
It also affects the optic nerve,causing blindness.

(N/A) When ethanol $(CH_{3}CH_{2}OH)$ reacts with sodium metal $(Na)$,it forms sodium ethoxide $(CH_{3}CH_{2}ONa)$ and releases hydrogen gas $(H_{2})$.
The balanced chemical equation for this reaction is:
$2CH_{3}CH_{2}OH + 2Na \rightarrow 2CH_{3}CH_{2}ONa + H_{2}$

(N/A) In this reaction,concentrated sulphuric acid acts as a dehydrating agent,which removes a water molecule from the ethanol molecule.
The balanced chemical equation is:
$CH_3CH_2OH \xrightarrow[443\, K]{\text{Hot conc. } H_2SO_4} CH_2=CH_2 + H_2O$

(N/A) Carbon tetrachloride $(CCl_4)$ is formed when carbon reacts with chlorine.
$(b)$ Carbon dioxide $(CO_2)$ is formed when carbon reacts with oxygen.

(N/A) The atomic number of chlorine is $17$. Its electronic configuration is $2, 8, 7$ in $K, L, M$ shells respectively.
$(b)$ Each chlorine atom has $7$ valence electrons. To complete its octet,each chlorine atom shares one electron with another chlorine atom,forming a single covalent bond. The electron dot structure is as follows:
:Cl:Cl: (with $6$ dots around each Cl and $2$ shared dots in the middle)

(N/A) Carbon exhibits catenation to a much greater extent than silicon.
This is primarily due to the smaller atomic size of carbon,which allows for the formation of strong and stable $C-C$ covalent bonds.
In contrast,silicon has a larger atomic size,which results in longer and weaker $Si-Si$ bonds,making them less stable compared to $C-C$ bonds.
Additionally,the high bond energy of the $C-C$ bond contributes to the extensive catenation observed in carbon compounds.

(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 $KMnO_4$.

(B) The correct matches are as follows:
$(a)$ $CH_{3}OH + CH_{3}COOH \xrightarrow{H^{+}} CH_{3}COOCH_{3} + H_{2}O$ is an Esterification reaction $(iv)$, where an alcohol and a carboxylic acid react to form an ester.
$(b)$ $CH_{2}=CH_{2} + H_{2} \xrightarrow{Ni} CH_{3}-CH_{3}$ is an Addition reaction $(i)$, where hydrogen is added across the double bond of an unsaturated hydrocarbon.
$(c)$ $CH_{4} + Cl_{2} \xrightarrow{\text{Sunlight}} CH_{3}Cl + HCl$ is a Substitution reaction $(ii)$, where a hydrogen atom in methane is replaced by a chlorine atom.
$(d)$ $CH_{3}COOH + NaOH \longrightarrow CH_{3}COONa + H_{2}O$ is a Neutralisation reaction $(iii)$, where an acid reacts with a base to form salt and water.
Therefore, the correct sequence is $(a)-(iv), (b)-(i), (c)-(ii), (d)-(iii)$.

(N/A) Hexane $(C_6H_{14})$ has five structural isomers:
$(a)$ $n$-Hexane: $CH_3-CH_2-CH_2-CH_2-CH_2-CH_3$
$(b)$ $2$-Methylpentane: $CH_3-CH(CH_3)-CH_2-CH_2-CH_3$
$(c)$ $3$-Methylpentane: $CH_3-CH_2-CH(CH_3)-CH_2-CH_3$
$(d)$ $2,2$-Dimethylbutane: $CH_3-C(CH_3)_2-CH_2-CH_3$
$(e)$ $2,3$-Dimethylbutane: $CH_3-CH(CH_3)-CH(CH_3)-CH_3$

(N/A) $Ni$ (Nickel) acts as a catalyst in the hydrogenation reaction.
$(b)$ Concentrated $H_{2}SO_{4}$ (Sulfuric acid) acts as a dehydrating agent and a catalyst in the esterification reaction.
$(c)$ Alkaline $KMnO_{4}$ (Potassium permanganate) acts as an oxidizing agent.

(N/A) The chemical equation for the reaction is:
$CH_{3}COOH + NaHCO_{3} \rightarrow CH_{3}COONa + H_{2}O + CO_{2}$
$X$ is sodium ethanoate $(CH_{3}COONa)$.
The gas evolved is carbon dioxide $(CO_{2})$.
Activity:
$1$. Take a test tube and add a small amount of sodium hydrogencarbonate $(NaHCO_{3})$ to it.
$2$. Add a few drops of ethanoic acid $(CH_{3}COOH)$ to the test tube.
$3$. You will observe effervescence due to the evolution of a gas.
$4$. Pass this gas through a delivery tube into another test tube containing lime water $(Ca(OH)_{2})$.
$5$. The lime water will turn milky,which confirms that the evolved gas is carbon dioxide $(CO_{2})$.
Chemical reaction with lime water:
$Ca(OH)_{2} + CO_{2} \rightarrow CaCO_{3} + H_{2}O$

(N/A) Hydrocarbons are organic compounds consisting entirely of carbon and hydrogen atoms. They serve as the fundamental building blocks of organic chemistry.
Examples include:
$1$. Methane $(CH_4)$
$2$. Ethane $(C_2H_6)$
$3$. Propane $(C_3H_8)$