Chapter 28.:CARBON AND ITS COMPOUNDS
Chapter 28: Carbon and Its Compounds Class 10 Science and Technology (212) NIOS Textbook Solutions
Chapter 28. CARBON AND ITS COMPOUNDS
NTEXT QUESTIONS 28.1
1. What is the valency of carbon?
Answer: The valency of carbon is 4.
2. What is the nature of bonds formed by carbon?
Answer: The bonds formed by carbon are covalent bonds.
3. Why carbon forms a large number of compounds?
Answer: Carbon forms a large number of compounds because it has the property of catenation, which allows it to form long chains and rings with other carbon atoms. It also shows isomerism, where compounds have the same formula but different structures, and forms compounds with various functional groups, increasing the variety of carbon compounds.
4. Name the branch of chemistry which is devoted to the study of carbon compounds.
Answer: The branch of chemistry devoted to the study of carbon compounds is organic Chemistry.
5. How many electrons are needed by a carbon atom to complete its octet?
Answer: A carbon atom needs 4 electrons to complete its octet.
INTEXT QUESTIONS 28.2
1. Which allotropic form of carbon has been discovered few years back?
Answer: The allotropic form of carbon discovered a few years back is fullerene.
2. Each carbon atom is linked to how many carbon atoms in
(i) Diamond
(ii) Graphite
Answer: (i) In diamond, each carbon atom is linked to 4 other carbon atoms.
(ii) In graphite, each carbon atom is linked to 3 other carbon atoms.
3. Why diamond has high melting point?
Answer: Diamond has a high melting point because a large amount of heat energy is required to break its strong three-dimensional network of covalent bonds.
4. Is diamond a conductor of electricity? Give reason for your answer.
Answer: No, diamond is not a conductor of electricity because it has no free electrons to carry electric current. All its valence electrons are used in forming strong covalent bonds.
5. Why is graphite a good lubricant?
Answer: Graphite is a good lubricant because the weak forces between its layers of carbon atoms allow the layers to slide over each other easily.
6. Give two uses of graphite.
Answer: Two uses of graphite are:
(i) As electrodes.
(ii) As a lubricant.
7. What kind of structure is possessed by fullerenes?
Answer: Fullerenes have a closed structure similar to a football.
8. Name the three microcrystalline forms of carbon and give their use.
Answer: The three microcrystalline forms of carbon and one use of each are:
(i) Charcoal is used for absorbing coloured impurities.
(ii) Coke is used as a reducing agent in metallurgy.
(iii) Carbon black is used as a pigment in inks or in automobile tyres.
INTEXT QUESTIONS 28.3
1. Classify the following compounds as organic or inorganic:
(i) Sugar
(ii) calcium carbide
(iii) kerosene
(iv) carbon dioxide
(v) carbon disulphide
Answer: The compounds are classified as follows:
(i) Sugar → Organic
(ii) Calcium carbide → Inorganic
(iii) Kerosene → Organic
(iv) Carbon dioxide → Inorganic
(v) Carbon disulphide → Inorganic
2. Give two differences between organic and inorganic compounds
Answer: The differences between organic and inorganic compounds :
|
Organic Compounds |
Inorganic Compounds |
|
Have low melting and boiling points. |
Have high melting and boiling points. |
|
Dissolve in organic solvents. |
Dissolve in water and not in organic solvents. |
INTEXT QUESTIONS 28.4
1. What is dry ice?
Answer: Dry ice is the solid form of carbon dioxide (CO₂).
2. Which gas, carbon monoxide or carbon dioxide, is a major air pollutant?
Answer: Carbon monoxide is the major air pollutant.
3. Which gas is used in carbonated drinks?
Answer: The gas used in carbonated drinks is carbon dioxide.
4. Name the gas which is a major contributor to the green house effect.
Answer: The gas that is a major contributor to the greenhouse effect is carbon dioxide.
5. Name the products obtained by the fermentation of sugar.
Answer: The products obtained by the fermentation of sugar are ethanol (ethyl alcohol) and carbon dioxide.
INTEXT QUESTIONS 28.5
1. What is the difference between saturated and unsaturated compounds?
Answer: In saturated compounds, single bonds are present between carbon atoms whereas in unsaturated compounds double or triple bonds are present between carbon atoms.
2. Give two examples each of (i) saturated compounds and (ii) unsaturated compounds.
Answer: (i) Saturated compounds: Methane (CH₄), Ethane (C₂H₆) .
(ii) Unsaturated compounds: Ethene (C₂H₄), Ethyne (C₂H₂).
3. Name the alkane which has three carbon atoms.
Answer: The alkane with three carbon atoms is propane (C₃H₈).
4. Define isomers.
Answer: Isomers are compounds which have the same molecular formula but have different structures.
5. What is the full form of IUPAC?
Answer: The full form of IUPAC : International Union of Pure and Applied Chemistry.
6. Name the following alkyl groups:
(i) -CH3
(ii) -C2H5
Answer: (i) – CH₃ — →Methyl group
(ii) – C₂H₅ — → Ethyl group
7. Give IUPAC name of these compounds
(a) CH 3 — CH2 — CH — CH 3 (b) CH 3 — CH — CH — CH 3
| | |
CH3 CH3 CH3
Answer: (a) 2-methylbutane
(b) 2,3-dimethylbutane
INTEXT QUESTIONS 28.6
1. Identify the functional groups present in the following compounds:
(i) CH3CH2OH
(ii) CH3Cl 
(iii) C2H2 
(iv) CH3-COOH 
In the next section, you will study about some simple compounds which contain some of the above mentioned functional groups.
Answer: The functional groups present are:
(i) CH₃CH₂OH – Alcohol (–OH)
(ii) CH₃Cl – Halo (–Cl)
(iii) C₂H₂ – Alkyne (–C≡C–)
(iv) CH₃COOH – Carboxylic acid (–COOH)
INTEXT QUESTIONS 28.7
1. What is wood alcohol?
Answer: Wood alcohol is methanol (CH₃OH).
2. What is glycerin? Which functional group is present in it.
Answer: Glycerin (glycerol) is a trihydric alcohol. It contains the hydroxyl (–OH) functional group.
3. How is ethanol produced?
Answer: Ethanol is produced by the fermentation of carbohydrates such as glucose and starch present in grapes, barley, etc.
4. Give two examples of compounds having aldehyde functional group.
Answer: Two examples of compounds having the aldehyde (–CHO) functional group are:
(i) Methanal (Formaldehyde)
(i) Ethanal (Acetaldehyde)
5. What is the use of acetone?
Answer: Acetone is used as a solvent.
6. Which acid is present in vinegar?
Answer: The acid present in vinegar is Acetic acid (CH₃COOH).
7. Name the compound which has an aldehyde group and is used as a flavour.
Answer: The compound that has an aldehyde group and is used as a flavour is Vanillin.
8. Give IUPAC Name of the following compounds
(a) C2H5OH 
(b) CH3COOH 
(c) HCHO
(d) CH3-CO-CH3 
Answer: The IUPAC names of the given compounds are:
|
Compound |
IUPAC Name |
|
(a) C₂H₅OH |
Ethanol |
|
(b) CH₃COOH |
Ethanoic acid |
|
(c) HCHO |
Methanal |
|
(d) CH₃COCH₃ |
Propanone |
9. Name the functional group present in the following compounds
(a) C2H5OH
(b) CH3COOH 
(c) HCHO (d) CH3-CO-CH3
Answer: The functional groups of the given compounds are:
|
Compound |
Functional Group |
|
(a) C₂H₅OH |
Alcohol (–OH) |
|
(b) CH₃COOH |
Carboxylic acid (–COOH) |
|
(c) HCHO |
Aldehyde (–CHO) |
|
(d) CH₃COCH₃ |
Ketone (>C=O) |
TERMINAL EXERCISES
1. Why carbon cannot form ionic bonds?
Answer: Carbon cannot form ionic bonds because it has four valence electrons. Losing four electrons requires a very large amount of energy, while gaining four electrons is highly unstable. Therefore, carbon forms covalent bonds by sharing electrons instead of forming ionic bonds.
2. What is catenation?
Answer: Catenation is the unique property of carbon by which carbon atoms bond with one another to form long chains, branched chains or rings through strong covalent bonds.
3. What types of bonds are formed by the carbon atom?
Answer: Carbon atoms form covalent bonds by sharing electrons. They can form single bonds, double bonds and triple bonds with other carbon atoms or with atoms of other elements.
4. Name the three allotropic forms of carbon.
Answer: The three allotropic forms of carbon are diamond , graphite and fullerene
5. How do natural diamonds form?
Answer: Natural diamonds are formed deep inside the Earth under very high temperature (about 1500°C) and very high pressure (about 70,000 atmospheres). Under these conditions, carbon atoms are converted into diamonds.
6. Name two places where diamonds are found.
Answer: Two places where diamonds are found are Panna (in Madhya Pradesh) and Wajrakarur (in Andhra Pradesh).
7. Why is diamond hard?
Answer: Diamond is hard because each carbon atom is strongly bonded to four other carbon atoms by strong covalent bonds, forming a rigid three-dimensional network. This makes diamond the hardest natural substance.
8. Give two uses of diamond.
Answer: Two uses of diamond are:
(i) It is used in cutting and grinding of other hard materials.
(ii) It is also employed in instruments used for cutting of glass and drilling of rocks.
(iii) It is used in jewellery.
9. Compare the physical properties of diamond and graphite.
Answer: The physical properties of diamond and graphite.
|
Diamond |
Graphite |
|
Hardest natural substance |
Soft and slippery |
|
Transparent |
Black and opaque |
|
Does not conduct electricity |
Good conductor of electricity |
|
High density |
Lower density than diamond |
10. How can graphite be converted into diamond?
Answer: Graphite can be converted into diamond by applying very high pressure and high temperature. Under these conditions, the arrangement of carbon atoms changes to form diamond.
11. Create a flow chart as shown below to compare the various allotropes of carbon
|
C |
||
|
G…… |
D…… |
F….. |
1. Names of Allotropes ............ ............ ............
2. Place where found ............ ............ ............
3. One use ............ ............ ............
4. Appearance ............ ............ ............
5. Arrangement of C atoms ............ ............ ............
Answer: 1. Names of allotropes
G: Graphite ; D: Diamond ; F: Fullerene
2. Place where found
G: In metamorphic rocks
D: In deep inside Earth (mines, kimberlite rocks)
F: In soot / interstellar space / laboratory synthesis
3. One use
G: Used in pencil lead / electrodes
D: Used in cutting tools / jewellery
F: Used in drug delivery / nanotechnology research
4. Appearance
G: Black, soft, slippery
D: Transparent, shiny, hard
F: Black or dark brown, spherical molecules
5. Arrangement of carbon atoms
G: Layered hexagonal sheets (weak forces between layers)
D: 3D tetrahedral network
F: Hollow spherical cage structure (buckyball)
12. What is activated charcoal? How is it prepared?
Answer: Activated charcoal is a finely powdered form of charcoal with a clean, porous surface that can adsorb impurities. It is prepared by heating charcoal with steam, which removes adsorbed substances and increases its adsorbing power.
13. Given below are pictures of three microcrystalline or amorphous form of graphite. Name them and write one use of each.
Picture of Charcoal Picture of Coke Picture of Carbon
from book from Book Black from book
A B C
Name ................................
Use ................................
Answer: A. Charcoal is used as a fuel or as an adsorbent in water purification.
B. Coke is used in the extraction of iron in blast furnaces.
C. Carbon black is used in the manufacture of tyres as a reinforcing agent.
14. Name the products formed when
(i) Wood is strongly heated in absence of air.
(ii) Coal is strongly heated in the absence of air.
(iii) Hydrocarbons are heated in limited supply of oxygen.
Answer: (i) When wood is strongly heated in the absence of air, the products formed are charcoal , wood tar and wood gas.
(ii) When coal is strongly heated in the absence of air, the products formed are Coke , Coal tar and Coal gas .
(iii) When hydrocarbons are heated in a limited supply of oxygen, the products formed are Carbon (soot) and carbon monoxide (CO).
15. Why is CO toxic in nature?
Answer: Carbon monoxide (CO) is toxic because it binds strongly with haemoglobin in the blood, reducing the blood's oxygen-carrying capacity. As a result, body tissues do not receive enough oxygen.
16. Give two uses of CO and CO2
.
Answer: Uses of Carbon Monoxide (CO):
(i) It is used as a fuel.
(ii) It is used in the synthesis of several organic compounds.
Uses of Carbon Dioxide (CO₂):
(ii) It is used in the production of carbonated drinks.
(iii) It is used in the production of washing soda and baking soda .
17. For the following state one point of differences between the following pairs of terms
(i) Organic compounds and inorganic compounds
(ii) Carbon Monoxide and carbon dioxide
(iii) Aliphatic and aromatic compounds
Answer: (i) Organic compounds and inorganic compounds:
Organic compounds generally contain carbon–hydrogen (C–H) bonds, whereas inorganic compounds generally do not contain C–H bonds.
(ii) Carbon monoxide and carbon dioxide:
Carbon monoxide (CO) is poisonous, whereas carbon dioxide (CO₂) is non-poisonous under normal conditions.
(iii) Aliphatic and aromatic compounds:
Aliphatic compounds have straight or branched carbon chains, whereas aromatic compounds contain benzene ring(s) in their structure.
18. What is a homologous series?
Answer: A homologous series is a family of organic compounds having the same functional group and similar chemical properties, in which each successive member differs by a –CH₂– group.
19. Name 10 carbon compounds of a homologous series. Write their molecular formula and derive a general formula for the series.
Answer: The first 10 members of the alkane homologous series are:
|
Carbon Compound |
Molecular Formula |
|
Methane |
CH₄ |
|
Ethane |
C₂H₆ |
|
Propane |
C₃H₈ |
|
Butane |
C₄H₁₀ |
|
Pentane |
C₅H₁₂ |
|
Hexane |
C₆H₁₄ |
|
Heptane |
C₇H₁₆ |
|
Octane |
C₈H₁₈ |
|
Nonane |
C₉H₂₀ |
|
Decane |
C₁₀H₂₂ |
From the molecular formulas, it is clear that each successive member differs by –CH₂. Therefore, the general formula of the alkane homologous series is CₙH₂ₙ₊₂.
20. What is general formula for the homologous series of
(i) alkanes (ii) alkenes (iii) alkynes?
Answer: The general formula of :
(i) Alkanes → CₙH₂ₙ₊₂
(ii) Alkenes → CₙH₂ₙ
(iii) Alkynes → CₙH₂ₙ₋₂
21. What is the molecular formula for ethane?
Answer: The molecular formula of ethane is C₂H₆.
22. Give here four prefixes: But- , Eth- , Meth- , Prop- , and Suffix –ane to develop the names of alkanes. How many carbon atoms do each of these alkanes contain?
Answer:
|
Prefix + Suffix |
Name of Alkane |
Number of Carbon Atoms |
|
Meth + ane |
Methane |
1 |
|
Eth + ane |
Ethane |
2 |
|
Prop + ane |
Propane |
3 |
|
But + ane |
Butane |
4 |
23. Draw the Chemical Structure of Butane and Isobutane and based on it justify that they are isomers.
Answer: Butane (n-butane):
CH3 – CH2 – CH2 – CH3
Isobutane (2-methylpropane):
CH3
|
CH3 – CH – CH3
Both butane and isobutane have the same molecular formula (C₄H₁₀) but different structural arrangements of carbon atoms. Therefore, they are isomers.
24. Give IUPAC name of the following compounds:
(i) CH3-CH = CH2 
(ii) CH3-HC = CH-CH3
(iii) CH3-OH
Answer: (i) CH₃–CH = CH₂ → Propene
(ii) CH₃–CH = CH–CH₃ → But-2-ene
(iii) CH₃–OH → Methanol
25. Give an example of a compound which has carboxylic ( – COOH) functional group.
Answer: An example of a compound containing the carboxylic (–COOH) functional group is ethanoic acid (CH₃COOH).
26. (a) Of the following which has single bond, double bonds and triple bonds between C, C atoms? Alkynes, alkane, alkene
(b) Name their simplest compounds and write the molecular formula.
Answer: (a)
Single bond (C–C)→ Alkanes
Double bond (C=C)→ Alkenes
Triple bond (C≡C)→ Alkynes
(b)
|
Type |
Simplest Compound |
Molecular Formula |
|
Alkane |
Methane |
CH₄ |
|
Alkene |
Ethene |
C₂H₄ |
|
Alkyne |
Ethyne |
C₂H₂ |
27. Give one use of each of the following:
(i) Methanol (ii) ethanol (iii) glycerin
Answer: (i) Methanol is used as a fuel.
(ii) Ethanol is used as an antiseptic in medicines and hand sanitizers.
(iii) Glycerin is used in the manufacture of soaps and cosmetics.
28. What is the difference between the structure of an aldehyde and a ketone?
Answer: An aldehyde has the –CHO functional group at the end of the carbon chain, whereas a ketone has the >C=O functional group in the middle of the carbon chain.
29. What is (i) dry ice (ii) wood alcohol (iii) formalin (iv) vinegar
Answer: (i) Dry ice: The solid form of carbon dioxide (CO₂).
(ii) Wood alcohol: Methanol (CH₃OH).
(iii) Formalin: An aqueous solution of formaldehyde (methanal).
(iv) Vinegar: A dilute aqueous solution of acetic (ethanoic) acid (about 5–8%).
30. To which group of carbon compounds do each of the carbon compounds used for the following belong?
(i) To ripen fruits
(ii) In oxy-acetylene torch
Answer: (i) To ripen fruits – Alkenes (Ethene)
(ii) In an oxy-acetylene torch – Alkynes (Ethyne/Acetylene
31. Name the carboxylic acid present in vitamin C.
Answer: The carboxylic acid present in Vitamin C is ascorbic acid.
32. Which acid is present in citrus fruits?
Answer: The acid present in citrus fruits is citric acid.
33. Your teacher has asked you to procure sources of formic acid and butyric acid. Which two sources will you collect and bring?
Answer: If my teacher asked me to procure sources of formic acid and butyric acid, I would collect ants, which are a source of formic acid, and rancid butter, which is a source of butyric acid.
34. Name the carboxylic acids found in :
(i) Lemon (ii) Vitamin C (iii) Sour milk (iv) Rancid butter (v) Ants
Answer: The carboxylic acids found in the following are:
(i) Lemon → Citric acid
(ii) Vitamin C → Ascorbic acid
(iii) Sour milk → Lactic acid
(iv) Rancid butter → Butyric acid
(v) Ants → Formic acid
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