Chap 4 : Carbon and Its Compounds www.cbse.

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CHAPTER 4
Carbon and Its Compounds

ONE MARK QUESTIONS (1) HCOOH Methanoic acid

(2) CH3COOH Ethanoic acid

8. Write the molecular formula of 2nd and 3rd member of

1. Write the molecular formula of first two members of
the homologous series whose first member is ethyne.
homologous series having functional group —Cl.
Ans : [CBSE 2017]
Ans : [CBSE 2017]
(1) HC / C—CH3 Propyne
(1) CH3Cl Chloromethane
(2) HC / C—CH2—CH3 1-Butyne
(2) CH3CH2Cl Chloroethane
9. Write the molecular formula of 2nd and 3rd member
2. Write the molecular formula of first two members of
of the homologous series whose first member is ethene.
homologous series having functional group —Br.
Ans : [CBSE 2017]
Ans : [CBSE 2017]
(1) CH2=CH—CH3 Propene
(1) CH3Br Bromomethane
(2) CH2=CH—CH2—CH3 1-Butene
(2) C2H5Br Bromoethane

3. Write the molecular formula of first two members of

homologous series having functional group —OH.
Ans : [CBSE 2017]
(1) CH3OH Methanol
(2) C2H5OH Ethanol

4. Write the molecular formula of 2nd and the 3rd

member of homologous series whose first member is
methane.
Ans : [CBSE 2017]
(1) CH3—CH3 Ethane
(2) CH3—CH2—CH3 Propane

5. Write the formula of first two members of homologous 10. Write the next homologue of each of the following:
series whose functional group is —CHO. a. C2H4
Ans : [CBSE 2017] b. C4H6
Ans : [CBSE 2016]
1. Methanal (1) C3H6, CH2=CH—CH3
(2) C5H8, HC=C—CH2—CH2—CH3

2. Ethanal 11. Name the following compounds:

a. CH3CH2OH
6. Write the formula of first two members of homologous
series whose functional group is .
Ans : [CBSE 2017] b.
Ans : [CBSE 2016]
a. Ethanol
1. 2-Propanone
b. Ethanal

12. Select the saturated hydrocarbons from the following:

2. 2-Butanone C3H6, C5H10, C4H10, C6H14, C2H4
7. Write the molecular formula of the first two members Ans : [CBSE 2016]
of the homologous series having functional group — C4H10, C6H14 are saturated hydrocarbons
COOH.
Ans : [CBSE 2017] 13. Write the name and structure of an alcohol with three
 carbon atoms in its molecules. 23. Write the next homologue of propanol CH3CH2CH2OH
Ans : [CBSE 2016] and butanal CH3CH2CH2CHO.
CH3CH2CH2OH, 1-Propanol Ans : [CBSE 2016,2011]
a. CH3CH2CH2CH2OH, Butanol
14. Write the name and structure of an alcohol with four b. CH3CH2CH2CH2CHO, Pentanal
carbon atoms in its molecule.
Ans : [CBSE 2016] 24. Unsaturated hydrocarbon gives a yellow flame with
lot of black smoke when burnt in oxygen. Give reason.
CH3CH2CH2CH2OH, 1-Butanol
Ans : [CBSE 2015]
15. Write the name and structure of an aldehyde with Unsaturated hydrocarbons have more amount of
four carbon atoms in its molecule. carbon, therefore burns with smoky flame due to
Ans : [CBSE 2016] incomplete combustion.

25. Write molecular formula of alcohol which can be

derived from butane.
Butanal Ans : .[CBSE 2015]
CH3CH2CH2CH2OH, 1-Butanol

16. Which element exhibits the property of catenation to 26. Carbon has four electrons in its valence shell. How
maximum extent and why? does carbon attain stable electronic configuration?
Ans : [CBSE 2016] Ans : [CBSE 2015]

Carbon because it can form strong covalent bond with Carbon can share four electrons to acquire stable
other carbon atoms due to smaller size. electronic configuration.

17. Write the name and formula of fourth member of 27. Write the name and formula of 2nd member of
alkane series. homologous series having general formula CnH2n.
Ans : [CBSE 2016] Ans : [CBSE 2015]

CH3—CH2—CH2—CH3, Butane CH2=CH—CH3 is second member of alkene.

18. What is a homologous series of carbon compounds? 28. Write the name and formula of 2nd member of
homologous series having general formulaC n H 2n + 2 .
Ans : [CBSE 2016]
Ans : [CBSE 2015]
Homologous series is series of organic compounds
which have same functional group and similar chemical CH3—CH3, Ethane
properties and each successive member has more — 29. Write the name and formula of 2nd member of
CH2 unit than the previous one. homologous series having general formula C n H 2n - 2 .
19. A colourless gas X has a formula C3H6. It decolourises Ans : [CBSE 2015]
bromine water. Write the chemical formula of ‘X’. HC / C—CH3, Propyne
Ans : [CBSE 2016]
30. Write the number of covalent bonds in the molecule
CH2=CH—CH3, Propene of propane, C3H6.
20. Draw the structural formula of methanoic acid. Ans : [CBSE 2015]
Ans : [CBSE 2016]
has 10 covalent bonds
Methanoic acid
31. Write the number of covalent bonds in the molecular
21. A molecule of ammonia has the formula NH3. Predict formula of butane, C4H10.
the total number of bonds present around nitrogen
Ans : [CBSE 2015]
atom.
Ans : [CBSE 2016]
has 13 covalent bonds
, it has three covalent bonds

32. Name the process by which unsaturated fats are

22. Write the number of covalent bonds in the molecule changed into saturated fats.
of ethane. Ans : [CBSE 2015]
Ans : [CBSE 2016,2015,2011 ] Hydrogenation

33. Write the name of each of the following functional

has 7 covalent bonds
 groups: compounds.
Ans : [CBSE 2014,2010]
a. —OH b. (a) Tetravalency (b) Catenation
Ans : [CBSE2015]
41. The molecular formula of A is C10H18 and B is C18H36.
a. Alcohol Name the homologous series to which they belong.
b. Ketone
Ans : [CBSE 2014]
34. Write the name and molecular formula of the first C10H18 belongs to alkyne, C18H36 belongs to alkene.
member of homologous series of alkynes.
Ans : [CBSE2015] 42. Write the names of next homologue of CH3CH2OH
and HCOOH.
HC=CH, Ethyne
Ans : [CBSE 2014]
35. Mention the functional group which always occurs at (i) CH3CH2CH2OH, Propanol
the terminal position of a carbon chain of an organic (ii) CH3COOH, Ethanoic acid
compound.
Ans : [CBSE 2015] 43. Will micelle formation take place when soap is
dissolved in organic solvent?
a. Aldehyde
b. Carboxylic acid Ans : [CBSE 2014]
No, micelles will not be formed in organic solvent.
36. The formula of citric acid is shown below:
44. Explain why washing clothes with hard water is not
effective.
Ans : [CBSE 2014]
Soap reacts with Ca 2+
and Mg 2+
ions present in hard
water to form scum.

45. Draw the structure of simplest ketone.

Ans : [CBSE 2014,2011]

State the name of —COOH functional group in citric

acid.
Ans : [CBSE 2014]
Carboxylic acid

37. Name the functional group in the following compounds:

a. CH3—CH2—CH2—COOH 46. Why do alkanes burn with blue flame?
b. CH3—CO—CH2—CH3
Ans : [CBSE 2013]
Ans : [CBSE 2014]
It is because they have less carbon and more hydrogen,
a. Carboxylic acid therefore, undergo complete combustion and produce
b. Ketone blue flame.
38. State the valency of each carbon atom in (i) an alkane 47. What happens when a small piece of sodium is
and (ii) an alkyne. dropped into ethanol?
Ans : [CBSE 2014] Ans : [CBSE 2013,2011]
i. The valency of ‘C’ in alkane is 4. Sodium ethoxide and H2 gas is formed
ii. The valency of ‘C’ in alkyne is also 4. 2C2H5OH + 2Na $ 2C2H5ONa + H2
39. Write the molecular formula of benzene and state the 48. What will you observe on adding a 5% alkaline KMnO4
number of double bonds in its structure. solution drop by drop to some warm ethanol taken in
Ans : [CBSE 2014] a test tube? Write the name of the compound formed
during the above chemical reaction.
Ans : [CBSE 2013,2011]
The purple colour of KMnO4 decolourises and ethanoic
is benzene or acid will be formed
Alk. KMNO
C2H5OH CH2OOH
4

ethanol ethanoic acid

These are 3 double bonds. 49. How is scum formed?

Ans : [CBSE 2012]
40. List two characteristic features of carbon which
when put together given rise to a number of carbon Ca 2+
and Mg
2+
ions react with soap (sodium stearate)
 to form calcium and magnesium stearate which is compounds.
insoluble in water and called scum.
59. Write the electron dot structure of ethene molecule
50. Name the functional group present in each of the (C2H4).
following organic compounds: Ans : [CBSE 2011]
a. C2H5—Cl
b. C2H5OH
Ans : [CBSE 2012]
a. Halogen
b. Alcohol
60. Write the electron dot structure of ethane molecule
51. Name the functional group present in each of the C2H6.
following compounds: Ans : [CBSE 2011]
a. HCOOH
b. C2H5CHO
Ans : [CBSE 2012]
a. Carboxylic acid
b. Aldehyde

52. Name the functional group present in each of the

61. Draw the structure of butanone molecule,
following compounds:
CH3COC2H5.
a. CH3COCH3
b. C2H5COOH Ans : [CBSE 2011]
Ans : [CBSE 2012]
a. Ketone
b. Carboxylic acid

53. Write the name and formula of the second member

of carbon compounds having functional group —OH. 62. Draw the structure of ethanoic acid molecule,
Ans : [CBSE 2012] CH3COOH.
CH3CH2OH, Ethanol Ans : [CBSE2011]

54. Write the name and formula of the first member of

series of carbon compound having functional group
—CHO.
Ans : [CBSE 2012]

63. Draw the structure of the hexanal molecule

Methanal
C5HnCHO.
55. Write the name and formula of the first member of Ans : [CBSE2011]
carbon compounds having functional group —COOH.
Ans : [CBSE 2012]

Methanoic acid

56. Write the name and formula of the 2nd member of the
series of carbon compounds whose general formula is 64. Butanone has four carbon per molecule of a compound.
CnH2n+1—OH. Name the functional group present in it.
Ans : [CBSE 2012] Ans : [CBSE 2011]

C2H5OH, Ethanol Ketone

57. Write the name and formula of 2nd member of the 65. Name the following compound:
series of carbon compounds whose general formula is
CnH2n.
Ans : [CBSE 2012]
CH2=CH—CH3, Propene
Ans : [CBSE 2011]
58. State the difference between oils and fats.
Ans : [CBSE Sample Paper 2012] 1-Hexyne

Oils are unsaturated whereas fats are saturated

66. Write the structural formula of chloroethane.
Ans : [CBSE 2010]

67. Name the carbon compound which on heating with

excess of cone. H2SO4 at 443 K gives ethene.
Ans : [CBSE 2009 (C)] Benzene has 3 double bonds whereas cyclohexane has
all single bonds.
Ethanol,
Conc. H 2 SO 4
CH3CH2OH CH2=CH2 + H2O 75. a. Write chemical name and formula of vinegar?
443 K
b. Describe with a chemical equation what happens
68. What is meant by saturated hydrocarbon? when sodium reacts with ethanol.
Ans : [CBSE 2009 (C)] Ans : [CBSE 2017,2012]
Those hydrocarbons in which valency of carbon is a. Vinegar contains ethanoic acid,
satisfied by single bonds only are called saturated
hydrocarbons.

69. Name the compound formed when ethanol is warmed b. Sodium ethoxide and hydrogen gas is formed.
with ethanoic acid in the presence of few drops of 2C2H5OH + 2Na $ 2C2H5ONa + H2
cone. H2SO4.
Ans : [CBSE 2009 (C)] 76. State reasons to explain why covalent compounds:
a. are bad conductors of electricity?
Ethyl ethanoate
Con. H 2 SO 4 b. have low melting and boiling points?
CH3COOH + CH3CH2OH T
Ans : [CBSE 2016]
CH3COOC2H5 + H2O a. Covalent compounds do not form ions, hence they
70. What is the difference in the molecular formula of
are bad conductor of electricity.
any two consecutive members of homologous series of b. Covalent compounds have weak intermolecular
organic compounds? forces of attraction, therefore, have low melting
and boiling points.
Ans : [CBSE 2008 (C)]
The difference between successive members of 77. What is homologous series? Write the name and draw
homologous series is of —CH2 unit. the structure of the second member of alkene series.
Ans : [CBSE 2016]
TWO MARKS QUESTIONS a. The series of organic compounds having same
functional group and similar chemical properties
is called homologous series.
71. Draw the structural formulae of the possible isomers b.
for the compound with molecular formula C3H6O.
Ans : [CBSE Sample Paper 2017]

72. Explain why cannot we have isomers of first three 78. List two characteristics of covalent compounds.
members of alkane family. Ans : [CBSE 2015]
Ans : [CBSE Sample Paper 2017, CBSE 2015] (i) They have low melting and boiling point.
It is because branching is not possible with carbon (ii) They do not conduct electricity.
atoms, that is why, there are no isomers till propane.
79. Name an element, other than carbon, which exhibits
73. Write balanced equations for the burning of (a) property of catenation up to seven or eight atoms. Are
methane (b) ethane in air. these compounds stable?
Ans : [CBSE 2017] Ans : [CBSE 2015]
(a) CH4(g) + 2O2(g) $ CO2(g) + 2H2O(l) Si and Sulphur (S8).
(b) 2C2H6(g) + 7O2(g) $ 4CO2(g) + 6H2O(l) No, these compounds are not stable, rather they are
reactive.
74. Compare the structures of benzene and cyclohexane
by drawing them. 80. Select alkenes and alkynes from the following:
C2H4, C3H4, C2H2, C4H8
Ans : [CBSE 2017]
Ans : [CBSE 2015,2014]
 Alkenes C2H4, C4H3 Alkynes C3H4, C2H2 88. Give the electron dot structure of chloro-methane. Also
write the formula and the name of next homologue of
81. Why are detergents preferred over soaps for washing it.
clothes in hard water? Explain.
Ans : [CBSE 2015]
Ans : [CBSE 2015,2014]
Detergents work well even with hard water because
their calcium and magnesium salts are soluble in
water. They do not form scum.

82. What happens when ethyl alcohol and acetic acid

react with each other in presence of cone. H2SO4?
Ans : [CBSE 2015,2013,2011]
Pleasant fruity smelling compound ester is formed
cone. H2SO4.
Con. H SO
CH3COOH + C2H5OH
2 4

T
CH3COOC2H5 + H2O
89. The structural formula of an ester is

83. Name the functional groups of the following

compounds:
a. b.
Write the structural formula of the corresponding
alcohol and acid.
c. R—OH d. R—X
Ans : [CBSE 2015]
Ans : [CBSE 2013]
a. Carboxylic acid
b. Ester
c. Alcohol
d. Halogen

84. Why is hydrogenation? What is its industrial

application? 90. How do the melting and boiling points of the
Ans : [CBSE 2015,2014] hydrocarbons change with increase in molecular mass?
Hydrogenation is a process of adding hydrogen to Ans : [CBSE 2012]
unsaturated compounds in presence of catalyst like Melting and boiling point of the hydrocarbons
nickel to form saturated hydrocarbons. Industrially, increases with increase in molecular mass because
it is used to convert vegetable oils to vegetable ghee. surface area increases which results an increase in
vander Waal’s forces of attraction between molecules.
85. List four characteristics of homologous series.
Ans : [CBSE 2014] 91. Write a chemical test to distinguish between ethanol
and ethanoic acid. [CBSE 2012]
a. All members are derived from same general
or
formula.
How would you distinguish experimentally between
b. All members have same functional group.
ethanol and ethanoic acid with the help of sodium
c. Each successive member differ by —CH2 unit.
hydrogen carbonate? Write the chemical equation for
d. All members can be prepared by same methods
the reaction involved.
of preparation.
Ans : [CBSE 2012]
86. Carbon does not form ionic compounds, why? Add NaHCO3 to each of them separately. Ethanol will
Ans : [CBSE 2015,2013] not react. Ethanoic acid will give brisk effervescence
Carbon cannot lose four electrons because high energy due to CO2.
is needed to remove four electrons. It cannot gain 4 CH3COOH + NaHCO3 $
electrons because 6 protons cannot hold 10 electrons. CH3COONa + H2O + CO2
That is why carbon cannot form ionic compounds. C2H5OH + NaHCO3 $ No reaction

87. What are soaps? Why do they form scum with hard 92. Explain the action of soap in removing an oily spot
water? from a piece of cloth.
Ans : [CBSE 2013] Ans : [CBSE 2011]
Soaps are sodium or potassium salts of fatty acids e.g. Cleansing action of soap: Soap has ionic end which
sodium stearate. They react with Ca2+ and Mg2+ ions is hydrophilic, interacts with water while carbon
in hard water to form calcium and magnesium salt chain is hydrophobic interacts with oil, grease. The
of fatty acids which are insoluble in water and called soap molecules orient themselves in a cluster in which
scum. hydrophobic tails are inside the cluster and ionic ends
 face outside. called homologous series.
These cluster are called micelles. These attract oil C2H6O(C2H5OH) and CH4O(CH3OH) belong to same
which is washed away by water. homologous series.

98. With the help of a suitable example explain in brief the

93. Draw electron dot structures of (i) C2H4 (ii) C2H5OH.
process of hydrogenation mentioning the conditions of
Ans : [CBSE 2011]
the reaction and also state any one physical property
of substances changes due to hydrogenation.
Ans : [CBSE 2010]
i.

ii. Liquid oil changes to solid ghee

94. Give reasons for the following:

a. Unsaturated hydrocarbons show addition
THREE MARKS QUESTIONS
reactions but not saturated hydrocarbons.
b. Carbon forms only covalent bonds. 99. A compound X on heating with excess of cone. H2SO4
Ans : [CBSE 2011] at 443 K gives an unsaturated compound Y. X also
a. Unsaturated hydrocarbons have double or triple reacts with sodium metal to evolve a colourless gas
bonds to which a molecule can be added whereas Z. Identify X, Y and Z. Write the equations of the
saturated hydrocarbons have single bonds chemical reaction of formation of Y and also write the
addition reaction cannot take place. role of conc. sulphuric acid in the reaction.
b. It cannot lose four electrons because high energy Ans : [CBSE 2016]
is required. It cannot gain four electrons because X is CH3CH2OH, Ethanol Y is Ethene, Z is H2.
6 protons cannot hold 10 electrons. Thus it shares Conc $ H SO
C 2 H 5 OH CH 2 = CH 2 + H 2 O
2 4

four electrons to form covalent bonds and become X

443K Y

stable. 2CH 3 CH 2 OH + 2Na $ 2CH 3 CH 2 ONa + H 2

Ethanol Sodium ethoxide Z

95. Write the name and molecular formula of an organic

Cone. H2SO4 acts as dehydrating agent.
compound having its name suffixed with ‘—ol’ and
having two carbon atoms in the molecule. With the 100. a.Why are most carbon compounds poor conductors
help of a balanced chemical equation indicate what of electricity?
happens when it is heated with excess of cone. H2SO4. b. Write the name and structure of a saturated
Ans : [CBSE 2010] compound in which carbon atoms are arranged in
a ring. Give the number of single bonds present in
this compound.
Ans : [CBSE 2018]
a. It is because covalent compounds do not form
ions, therefore, do not conduct electricity.

96. Write the names and molecular formulae of two

organic compounds having functional group suffixed b.
as ‘—oic acid’. With the help of a balanced chemical
equation explain what happens when any one of them
reacts with sodium hydroxide.
Ans : [CBSE 2010]
HCOOH and CH3COOH It has 18 single bonds.
Methanoic acid Ethanoic acid
HCOOH + NaOH $ HCOONa + H2O 101. Draw the structural formula of all the possible isomers
It is an acid-base reaction where a salt i.e., sodium of the compound with the molecular formula C3H6O
methanoate and H2O is formed. and also give electron dot structures.
Ans : [CBSE Sample Paper 2018] [CBSE 2013]
97. What is homologous series? Which of the following
organic compounds belong to the same homologous
series?
C2H6, C2H6O, C2H6O2, CH4O
Ans : [CBSE 2010]
The series of organic compounds having same
functional group and similar chemical properties is
 106. Two carbon compounds ‘X’ and ‘Y’ have the molecular
formula C3H6 and C4H10 respectively. Which one of the
two is most likely to show addition reaction? Justify
your answer. Also give chemical equation to explain
the process of addition in this case.
Ans : [CBSE 2017]
C3H6 will undergo addition reaction because it has
double bond.
Ni
CH2=CH—CH3 + H2 Heat CH3—CH2—CH3
Propene Propane

107. Complete the following chemical reactions:

a. C2H5OH + O2 $
102. An aldehyde as well as ketone can be represented by Conc. H SO
b. C2H5OH
2 4

the same molecular formula say C3H6O. Write their 443 K

structures and name them. State the relationship c. CH3COOH + NaHCO3 $

between two in language of science. Ans : [CBSE 2017]
Ans : [CBSE Sample Paper 2017-2018, CBSE 2016] a. C2H5OH + 3O2 $ 2CO2 + 3H2O
Con. H SO
b. C2H5OH CH2=CH2 + H2O
2 4

443 K

c. CH3COOH + NaHCO3 $
CH3COONa + H2O + CO2

108. The molecular formula of two carbon compounds

are C4H3 and C3H8. Which one is most likely to show
addition reaction? Justify your answer. Also give the
These are functional isomers.
chemical equation to explain the process of addition
103. The carbon compounds X and Y have the molecular reaction in this case.
formula C4H3 and C5H12 respectively. Which one of Ans : [CBSE 2017]
these is most likely to show addition reaction? Justify C4H3 will undergo addition reaction. It is because it is
your answer. Also give chemical equations to explain unsaturated compound.
the process of addition reaction in this case.
Ans : [CBSE 2017]
C4H3 will undergo addition reaction. It is because it has
double bond while C5H12 is a saturated hydrocarbon
which cannot undergo addition reaction.
109. Write the structural formula of ethanol. What happens
when it is heated with excess of conc. H2SO4 at 443 K?
Write the chemical equation for the reaction stating
the role of cone. H2SO4 in this reaction.
Ans : [CBSE 2017]
104. Complete the following equations: CH3CH2OH, Ethanol
Con. H SO
C2H5OH CH2=CH2 + H2O
2 4
a. CH3COOC2H5 + NaOH $ 443 K
b. CH3COOH + NaOH $
Conc. H SO Concentrated H2SO4 is dehydrating agent.
c. C2H5OH + CH3COOH
2 4

Ans : [CBSE 2017] 110. Distinguish between esterification and saponification

reaction with the help of equations for each. State one
a. CH3COOC2H5 + NaOH $ CH3COONa +
use of each (i) esters and (ii) saponification process.
C2H5OH
b. CH3COOH + NaOH $ CH3COONa + H2O Ans : [CBSE 2017]
Con. H SO
c. C2H5OH + CH3COOH CH3COOC2H5 Esterification
2 4

Con. H 2 SO 4
+ H2O C2H5OH + CH3COOH
CH3COOC2H5 + H2O
105. Complete the following reactions: Ester

a. CH3COOH + N2CO3 $ Saponification

b. CH4 + O2 $ CH3COOC2H5 + NaOH $
c. C2H5OH + Na $ CH3COONa + C2H5OH
Ans : [CBSE 2017] Esters are used in synthetic flavours, perfumes, etc.
Saponification process is used for manufacture of
a. 2CH3COOH + Na2CO3 $ 2CH3COONa + H2O
soaps.
+ CO2
b. CH4 + 2O2 $ CO2 + 2H2O 111. What happens when:
c. 2C2H5OH + 2Na $ 2C2H5ONa + H2 (Write chemical equation in each case)
 a. Ethanol is burnt in air? 114. Explain giving reasons, why carbon can neither form
b. Ethanol is heated with excess cone. H2SO4 at 443 C4+ cation nor C4- anion but forms covalent compounds
K? which are bad conductors of electricity and have low
c. A piece of sodium is dropped in ethanol. melting and boiling points.
Ans : [CBSE 2017] Ans : [CBSE 2017]
a. CO2 and H2O are formed. Carbon cannot lose four electrons because high energy
C2H5—OH + 3O2 $ 2CO2 + 3H2O is needed to remove four electrons. It cannot gain 4
b. Ethene is formed electrons because 6 protons cannot hold 10 electrons.
Con. H SO
CH3CH2OH CH2=CH2 + H2O
2 4

443 K It can share 4 electrons to form covalent bonds.

c. Hydrogen gas evolves out Covalent compounds do not conduct electricity
2CH3CH2OH + 2Na $ 2CH3CH2ONa + H2 because these do not form ions. They have low melting
and boiling points due to weak force of attraction
112. Explain esterification reaction with the help of a between molecules.
chemical equation. Describe an activity to show
esterification. 115. Write the molecular formula of benzene and draw
its structure. List in tabular form how covalent
Ans : [CBSE 2017]
compounds differ from ionic compounds.
Esterification is the process in which carboxylic Ans : [CBSE 2017]
acid reacts with alcohol in presence of conc. H2SO4 to
form pleasant fruity smelling compound ester.
ConcH SO
C2H5OH + CH3COOH
2 4

CH3COOC2H5 + H2O
Activity:
To carry out esterification reaction.
• Take 2 mL of ethanol (100% alcohol) in a test
tube.
• Add 2 mL of glacial acetic acid.
• Add few drops of conc. H2SO4.
• Set the apparatus as shown in diagram. Covalent compounds Ionic compounds
• Heat the mixture in test tube in water bath for 5
to 10 minutes observe what happens. 1. They are bad con- They are good conduc-
• Observation: Pleasant fruity smell is observed. ductor of electricity. tor of electricity.
• Conclusion: Ester is formed. 2. They have low They have high melting
melting and boiling and boiling points.
points.

116. What are hydrocarbons? Write the general formula

of (a) saturated hydrocarbons (b) unsaturated
hydrocarbons and draw the structure of one
hydrocarbon of each type.
Ans : [CBSE 2017]
Hydrocarbons are compounds of carbon and hydrogen
only
a. CnH2n+2 is general formula of saturated
hydrocarbon. For example, CH4

113. Name two oxidising agents that are used to convert

alcohols to acids. Distinguish between ethanol and b. CnH2n(alkenes) and CnH2n-2 (alkynes) are general
ethanoic acid on the basis of (a) litmus test (b) formulae of unsaturated hydrocarbons. For
reaction with NaHCO3. example,
Ans : [CBSE 2017]
These two oxidising agents will convert alcohols to
acids (i) Alkaline KMnO4 (ii) Acidified K2Cr2O7
a. Litmus test: Acetic acid turns blue litmus red but 117. What is an oxidising agent? What happens when
ethanol does not. oxidising agent is added to propanol? Explain with
b. NaHCO3 test: Acetic acid will give brisk the help of a chemical equation.
effervescence due to evolution of CO2 whereas Ans : [CBSE 2016]
ethanol will not react.
Oxidising agent is a substance which adds oxygen
or remove hydrogen. Propanol will get oxidised to
 propanoic acid. a.
Alkaline KMnO4
CH3CH2CH2OH + 2(O)
CH3CH2COOH+ H2O
b.
118. What are covalent compounds? Why are they different
from ionic compounds? List three characteristic
properties.
Ans : [CBSE 2016]
c.
Those compounds in which bonds are formed by
sharing of electrons are covalent compounds.
While ionic compounds are formed by complete
transfer of electrons.
122. Write three different chemical reactions showing the
Covalent compounds Ionic compounds conversion of ethanoic acid to sodium ethanoate.
Write balanced chemical equation in each case. Write
1. They have weak They have strong
the name of the reactants and products other than
intermolecular forces intermolecular forces of
ethanoic acid and sodium ethanoate in each case.
of attraction. attraction.
Ans : [CBSE 2016]
2. They have low They have high
melting and boiling melting and boiling a.
points. points.
3. They do not They conduct electrici- b.
conduct electricity. ty in molten state or in
aqueous solution.

119. When ethanol reacts with ethanoic acid in presence of c.

cone. H2SO4, a substance with fruity smell is produced.
Answer the following questions:
a. State the class of compounds to which fruity
smelling compounds belong. Write the chemical
equation and write the chemical name of the
product formed.
123. An organic compound ‘P’ is a constituent of wine.
b. State the role of cone. H2SO4 in this reaction.
‘P’ on reacting with acidified K2Cr2O7 forms another
Ans : [CBSE 2016] compound ‘Q’. When a piece of sodium is added to
a. The fruity smelling compounds are esters ‘Q’ a gas ‘R’ evolves which burns with a pop sound.
CH 3 COOH + C 2 H 5 OH
Con.H 2 SO 4
CH 3 COOC 2 H 5 + H 2 O Identify P, Q and R and write the chemical equations
Ethanoic acid Ethanol Ethyl Ethanoate Water of the reactions involved.
b. Cone. H2SO4 acts as dehydrating agent. Ans : [CBSE 2016]
120. Name the compound formed when ethanol is heated
with excess of cone. H2SO4 at 443 K. Also write the
chemical equation of the reaction stating the role of
cone. H2SO4 in it. What would happen if hydrogen is
added to the product in presence of catalyst such as Q is ethanoic acid,
Pd or Ni?
Ans : [CBSE 2016]

124. a. Define the term functional group. Identify the

functional group present in
Cone. H2SO4 acts as dehydrating agent.

b. What happens when 5% alkaline KMnO4 solution

121. Write the chemical equation of the reaction of ethanoic is added drop by drop to warm ethanol taken in
acid with the following: a test tube? State the role of alkaline KMnO4
a. Sodium solution in this reaction.
b. Sodium hydroxide, Ans : [CBSE 2016]
c. Ethanol.
Write the name of one main product of each reaction. a. Functional group is an atom or group of atoms
which determine chemical properties of organic
Ans : [CBSE 2016]
compounds. (a) Aldehyde, (b) Carboxylic acid.
 b. Ethanoic acid is formed.
5%alkaline
CH3 CH2 OH + 2 [O] KMnO 4
CH 3 COOH
KMnO4 acts as oxidising agent.

125. Under which condition an oxidation reaction can be

called as combustion reaction. Illustrate your answer Esterification is the process of forming ester
with example.
129. Write any three physical properties and three uses of
Ans : [CBSE 2016]
ethanol.
When oxidation reaction produces heat as well as Ans : [CBSE 2016]
light it is called combustion reaction.
CH4 + 2O2 $ CO2 + 2H2O + heat + light Properties
It is oxidation as well as combustion reaction. a. Ethanol has specific smell.
b. It is soluble in water.
126. a.Give chemical tests to detect the presence of (a) c. It has burning taste.
ethanol (b) ethanoic acid. Uses
b. Why ethanoic acid is called glacial acetic acid? a. It is used as solvent.
Ans : [CBSE 2016] b. It is used as an antiseptic.
c. It is used in wine, beer, whisky, etc.
(i) (a) Ethanol reacts with Na to liberate d. It is used for preparation of ethanoic acid, ethyl
H2 gas ethanoate (esters).
2CH 3 CH 2 OH + 2Na $ 2CH 3 CH 2 ONa + H 2
(b) Ethanoic acid gives brisk effervescence of CO2 130. Explain the following reactions with chemical
with NaHCO3 equations:
CH 3 COOH + NaHCO 3 $ a. Oxidation
CH 3 COONa + H 2 O + CO 2 b. Hydrogenation
(ii) It is because pure acetic acid (anhydrous) solidifies c. Substitution
into solid crystals just below the room temperature at Ans : [CBSE 2016]
16.7°C and look like glacier of snow.
a. Oxidation
127. a.Chemical properties of ethanol is different from
methyl ethanoate. Justify the statement with
proper reason.
b. Methyl ethanoate is used in making perfume.
Justify. b. Hydrogenation
c. Ethanol is converted into ethene when excess of
cone. H2SO4 is added. Justify with the help of
reaction. c. Substitution
Ans : [CBSE 2016]
a. Chemical properties of a compound depends on its
functional group. Ethanol and methyl ethanoate
131. C3H6, C4H8 and C5H10 belong to same 1 homologous
have different functional group thus behave
series.
differently. CH3CH2OH has functional group —
a. Define homologous series.
OH. It has specific smell, reacts with Na metal
b. Why the melting and boiling point of C5H10 is
to liberate H2. CH2COOCH3 has ester (RCOOR’)
higher than C4H3?
as functional group. It has pleasant fruity smell,
c. Arrange these hydrocarbons in order of increasing
undergoes saponification reaction with NaOH.
boiling points.
b. It is due to pleasant fruity smell.
c. Conc H2SO4 dehydrates ethanol to ethene. Ans : [CBSE 2016]
ConcH SO
CH 3 CH 2 OH CH 2 = CH 2 + H 2 O a. The series of organic compounds having same
2 4

443K
functional group and similar chemical properties
128. The structural formula of an ester is is called homologous series.
b. C5H10 has higher molecular mass, more surface
area, more van der Waal’s forces of attraction,
hence higher boiling point than C4H8.
c. C3H6 < C4H8 < C5H10
Write the structural formula of the acid and the
132. The general formula of three compounds A, B and C
alcohol from which it might be prepared. Name the
is C n (H 2n . ‘B’ has highest boiling point and ‘C’ has
process of formation of an ester.
lowest boiling point.
Ans : [CBSE 2016] a. Mention the type of compounds A, B, C.
b. Which of these have minimum number of carbon
atoms?
c. Name the homologous series to which A, B and
 C belong. this reaction is referred to as substitution reaction.
Ans : [CBSE 2016] Ans : [CBSE 2015]
a. A, B, C are unsaturated compounds.
b. C has minimum number of carbon atoms..
c. They belong to alkene homologous series.

133. Draw the electron dot structure of ethyne. A mixture

of ethyne and oxygen is burnt for welding. In your Sunlight
opinion, why cannot we use a mixture of ethyne and CH2Cl2 + Cl2 CHCl 3
+ HCl
Trichloromethane
air for this purpose? Sunlight
CHCl3 + Cl2 CCl + HCl
Ans : [CBSE 2015] 4
Tetrachloromethane

This reaction is called substitution reaction because

HC / CH, Ethyne, hydrogen atom is being substituted by ‘Cl’ in each
step.
Ethyne and oxygen will produce lot of heat on
combustion needed for welding whereas ethyne and 138. What is difference between the molecule of soaps and
air will not produce enough heat needed for welding detergents, chemically? Explain the cleansing action
purposes. of soaps.
Ans : [CBSE 2015]
134. Classify the following carbon compounds into two
homologous series and name them. Soaps are sodium or potassium salts of fatty acids.
C3H4, C3H6, C4H6, C4H8, C5H8, C5H10 They contain —COONa group. Detergents are sodium
or potassium salts of sulphonic acids. They contains
Ans : [CBSE 2015]
—SO3Na or —SO4Na group. Soap has ionic end which
The series of organic compounds having same is hydrophilic, interacts with water while carbon
functional group and similar chemical properties is chain is hydrophobic interacts with oil, grease. The
called homologous series. soap molecules orient themselves in a cluster in which
Alkene: C3H6, C4H8, C5H10 hydrophobic tails are inside the cluster and ionic ends
Alkyne: C3H4, C4H6, C5H3 face outside. These cluster are called micelles. These
attract oil which is washed away by water.
135. Write the name and general formula of a chain of
hydrocarbons in which an addition reaction with 139. What is meant by isomers? Draw the structures of two
hydrogen is possible. State the essential conditions for isomers of butane, C4H10. Explain why we cannot have
an addition reaction. Stating this condition, write a isomers of first three members of alkane series.
chemical equation giving the name of the reactant and Ans : [CBSE 2015]
the product of the reaction.
Isomers are those compounds which have same
Ans : [CBSE 2015]
molecular formula but different structural formula.
Alkenes C n H 2n Alkynes C n H 2n - 2 CH3– CH2– CH2– CH3
In above two series of hydrocarbons, addition of H2 Butane
is possible.
Hydrogen is added in presence of nickel as catalyst
and heating is needed.

140. Write the molecular formula of the following

136. Why should we prefer vegetable oils over animal fats compounds and draw their electron dot structures:
for cooking food? Give a balanced chemical equation (a) Ethane (b) Ethene (c) Ethyne
for reaction of hydrogenation of vegetable oils. Name Ans : [CBSE 2015]
the catalyst in the reaction.
Ans : [CBSE 2015]
Vegetable oils are unsaturated and do not lead to a. , , C2H6
formation of cholesterol. Animals fats are saturated
lead to formation of cholesterol which can be deposited
in arteries.

b. , , C2H4

c. , , C2H2
137. Convert CH4 into CC14 by substituting hydrogen
atom with chlorine atom in successive reactions. Why
141. Why is homologous series of carbon compounds so
 X
called? Write the chemical formula of two consecutive KMnO 4 /KOH
members of any two homologous series and state the CH3CH2OH + 2[O] CH3COOK
part of these compounds that determines their (a) H+
CH3COOH + K+
physical and (b) chemical properties.
X is CH3COOC2H5, ethyl ethanoate.
Ans : [CBSE 2015]
Homologous means members of same family that 145. What is meant by homologous series of carbon
is why series of carbon compounds having same compounds? Write the general formula of (i) alkenes,
functional group and similar properties is called and (ii) alkynes. Draw the structures of the first
homologous series. member of each series to show the bonding between
Homologous series of alcohol. the two carbon atoms.
CH3OH Methanol Ans : [CBSE 2014]
C2H5OH Ethanol The series of organic compounds having same
CH3— and C2H5— groups determine physical functional group and similar chemical properties is
properties and —OH group determines chemical called homologous series.
properties. Homologous series of aldehyde. i. Alkenes CnH2n
CH3OH Ethanol
C2H5OH Propanal
Here, CH3—and C2H5— groups determine physical
properties while —CHO group determines chemical
properties.
ii. Alkynes CnH2n–2
142. What are esters? How are they prepared? List two
uses of esters.
Ans : [CBSE 2014]
Esters are pleasant fruity smelling compounds with 146. Write the chemical equations to show what happens
general formula R—COOR’. They are prepared by when
reaction of carboxylic acid and alcohol in presence a. an ester reacts with a base?
of cone. H2SO4. b. methane is treated with chlorine in the presence
Conc. H SO
CH3COOH + C2H5OH
2 4

of sunlight?
CH3COOC2H5 + H2O c. ethanol reacts with ethanoic acid in the presence
Uses of sulphuric acid?
i. They are used in cold drinks and ice creams as Ans : [CBSE 2014]
synthetic flavours.
ii. They are used in perfumes. a. CH3COOC2H5 + NaOH
CH3COONa + C2H5OH
143. State the meaning of functional group in an organic Sunlight
b. CH4 + Cl2 CH3Cl + HCl
compound. Write the formula of the functional group
present in alcohols, aldehydes, ketones and carboxylic c. CH3COOH + C2H5OH
Conc. H 2 SO 4

acids. CH3COOC2H5 + H2O

Ans : [CBSE 2014]
147. Write the respective chemical equations to show what
Functional group is an atom or group of atoms which
determine chemical properties of organic compounds happens when
(a) Aldehyde, (b) Carboxylic acid. a. methane is burned in presence of oxygen?
b. ethanol is heated with concentrated sulphuric acid
at 443 K?
–OH Alcohol; Aldehyde c. ethanol reacts with ethanoic acid in the presence
of an acid acting as a catalyst?
Ans : [CBSE 2014]

Ketone; Carboxylic acid a. CH4 + 2O2 CO + 2H2O

2
Conc. H 2 SO 4
b. CH3CH2OH 443 K
CH2=CH2 + H2O
144. A carboxylic acid (molecular formula C2H4O2) reacts Conc. H 2 SO 4
with an alcohol in the presence of an acid catalyst to c. CH3COOH + C2H5OH
form a compound X. The alcohol on oxidation with CH3COOC2H5 + H2O
alkaline KMnO4 following by acidification gives the
148. Write chemical equations to describe two different
same carboxylic acid C2H4O2. Write the name and
oxidations of ethanol. List two uses of ethanol.
structure of (i) carboxylic acid, (ii) alcohol and (iii)
the compound ‘X’. Ans : [CBSE 2015]
K 2 Cr2 O 7 /H 2 SO 4
Ans : [CBSE 2014,2013] CH3CH2OH + 2[O] CH3COOH
Conc. H 2 SO 4
CH3COOH + C2H5OH CH2CH2OH + O2 CO2 + H2O + Heat + Light
Ethanoic acid Ethanol Ethanol is used as an antiseptic and solvent
CH3COOC2H5 + H2O
149. A carbon compound X turns blue litmus to red and
 has a molecular formula C2H4O2. Identify X and draw compounds. (1) Alcohol, (2) Carboxylic acid.
its structure. Write chemical equation for the reaction a. Soaps do not work well with hard water as form
and name of the product formed in each case when X insoluble scum whereas detergents work well with
reacts with hard water.
a. ethanol in the presence of concentrate H2SO4.
b. sodium carbonate. 153. Give reasons for the following observations:
a. The element carbon forms a very large number of
Ans : [CBSE 2013]
compounds.
X is CH3COOH b. Air holes of a gas burner have to be adjusted when
the heated vessels get blackened by the flame.
c. Use of synthetic detergents causes pollution of
water.
Ans : [CBSE 2009]

a. CH3CH2OH
Conc. H 2 SO 4
CH2=CH2 + H2O a. It is due to tetravalency of carbon and property of
443 K
catenation shown by carbon to maximum extent.
b. 2CH3COOH + Na2CO3 $ b. Air holes must be kept open fully so that complete
2CH3COONa + H2O + CO2 combustion of fuel takes place producing blue
flame.
150. What is meant by isomers? “We cannot have isomers c. Some of detergents are not bio¬degradable, they
of first three members of alkane series.” Give reason create water pollution.
to justify this statement. Draw the structures of two
isomers of pentane, C5H12. 154. a.Why are covalent compounds generally poor
Ans : [CBSE 2013] conductors of electricity?
b. Name the following compound:
Isomers are those compounds which have same
molecular formula but different structural formula.
CH3– CH2– CH2– CH2– CH3
Pentane

c. Name the gas evolved when ethanoic acid is

added to sodium carbonate. How will you test the
presence of this gas.
Ans : [CBSE 2008]
151. An ester has the molecular formula C4H8O2. Write its a. It is because they do not form ions in their
structural formula. What happens when this ester is aqueous solution.
heated in the presence of sodium hydroxide solution? b. Propanone
Write the balanced chemical equation for the reaction c. Carbon dioxide gas will be liberated. Test: Pass
and name the products. What is a saponification the gas through lime water. If lime water turns
reaction. milky it shows the presence of CO2 gas.
Ans : [CBSE 2010]
FIVE MARKS QUESTIONS
is structural formula.
155. You are given balls and stick model of six carbon
When ester is heated with NaOH, sodium salt of acid
atoms and fourteen hydrogen atoms and sufficient
and alcohol are formed. It is called saponification
number of sticks. In how many ways one can join the
reaction.
models of six carbon atoms and fourteen hydrogen
atoms to form different molecules of C6H14.
Ans : [CBSE Sample Paper 2017-2018]
There are five ways in which six carbons can be joined
with 14 hydrogen atoms.

i.
152. a.What is meant by a functional group in an organic
compound? Name the functional group present in
(1) CH3CH2OH
(2) CH3COOH
b. State one point of difference between soap and
synthetic detergent. ii.
Ans : [CBSE2009]
a. Functional group is an atom or group of atoms
which determine chemical properties of organic
 iii.

Alkene CnH2n

iv. Alkyne CnH2n–2 Ethyne

Hydrogenation i.e. addition of H2 leads to formation of
alkanes from alkenes.
Ni
CH2 = CH2 + H2 heat CH3 – CH3

158. Complete the following chemical equations and write

v.
the chemical name of the products formed.
a. CH2=CH2 + H2 $
b. CH3COOH + NaOH $
H SO
c. CH3CH2OH
2 4

Check Anser : d. HCOOH + Na $

Alk $ MnO
e. C2H5OH
4

156. Soaps and detergents are both types of salts. State

the difference between the two. Write the mechanism Ans : [CBSE 2018]
of the cleansing action of soaps. Why do soaps not
a. CH2= CH2 + H2 CH3– CH3
form lather (foam) with hard water? Mention any
two problems that arise due to the use of detergents Ethane

instead of soaps. b. CH3COOH + NaOH

Ans : [CBSE 2017] CH3COONa + H2O
Sodium ethanoate
a. Soaps are sodium or potassium salts of fatty c. CH3CH2OH
Conc. H 2 SO 4
CH2= CH2 + H2O
D
acids e.g. —COONa. Detergents are sodium or Ethene

potassium salts of sulphonic acids e.g. —SO3Na d. 2HCOOH + 2Na 2HCOONa + H2

or —SO4Na Alk. KMnO 4
Sodium methanoate

b. Soaps are sodium or potassium salts of fatty e. C2H5OH CH3COOH + H2O

acids. They contain —COONa group. Detergents Ethanoic acid
are sodium or potassium salts of sulphonic acids.
They contains —SO3Na or —SO4Na group. Soap 159. a.Give a chemical test to distinguish between
has ionic end which is hydrophilic, interacts with saturated and unsaturated hydrocarbons.
water while carbon chain is hydrophobic interacts b. Name the products formed when ethane burns in
with oil, grease. The soap molecules orient air. Write the balanced chemical equation for the
themselves in a cluster in which hydrophobic tails reactions showing two types of energies liberated.
are inside the cluster and ionic ends face outside. c. Why is reaction between methane and chlorine in
These cluster are called micelles. These attract oil presence of sunlight is considered a substitution
which is washed away by water. reaction.
c. Soaps react with Ca2+ and Mg2+ ions in hard water Ans : [CBSE 2016]
to form calcium or magnesium salts of fatty acids a. Saturated hydrocarbons will not react with
which are insoluble in water and thus interfere in bromine water whereas unsaturated hydrocarbons
action of soap, will decolourise it.
d. (i) Detergents are more expensive than soaps. b. Carbon dioxide and water will be formed.
(ii) Some detergents are not biodegradable i.e. 2C2H6 + 7O2 $ 4CO2(g) + 6H2O(l)
will create pollution. + Heat + Light
157. Why are certain compounds called hydrocarbons? c. It is because hydrogen atom is substituted by
Write the general formula for homologous series of halogen atom, that is why it is called substitution
alkanes, alkenes and alkynes and also draw the reaction.
structure of the first member of each series. Write 160. a.You have three unlabelled test tubes containing
the name of the reaction which converts alkene into ethanol, ethanoic acid and soap solution. Explain
alkane. Also write the chemical equation to show the the method you would use to identify the
necessary conditions for the reaction to occur. compounds in different test tubes by chemical
Ans : [CBSE 2017] tests using litmus paper and sodium metal.
Compounds of carbon and hydrogen are called b. Give reason of formation of scum when soaps are
hydrocarbons. used with hard water.
Alkane CnH2n+2 Ans : [CBSE 2016]
 a. Red litmus paper will become blue in soap solution the concerned chemical reaction.
only. Ethanoic acid will turn blue litmus red only. (1) Ethanol to ethene
Ethanol will react with Na metal to form sodium (2) Ethanol to ethanoic acid
ethoxide and hydrogen gas will be liberated. b. Give one example with chemical equation for the
b. Soaps are sodium or potassium salts of fatty acids following reactions:
which react with Ca2+ and Mg2+ ions in hard water (1) Substitution reaction
to form calcium or magnesium salts of fatty acids (2) Saponification reaction
which are insoluble in water called scum. (3) Combustion reaction
Ans : [CBSE 2014]
161. What are micelles? Why does it form when soap is
Conc. H 2 SO 4
added to water? Will a micelle be formed in other a. (1) CH3CH2OH D
CH2= CH2 + H2O
solvents such as ethanol also? State briefly how the Ethanol Ethene

formation of micelles help to clean the clothes having (2) CH3CH2OH

K 2 Cr2 O 7 /Conc. H 2 SO 4

oily spots. CH3COOH + H2O

Ans : [CBSE 2016] b. (1) Substitution reaction
Micelles are cluster of molecules in which hydrophobic CH4 + Cl2
Sunlight
CH3Cl + HCl
tails are inside the cluster 3 and the ionic ends are at
the surface of clusters. Soap molecules when dissolved (2) Saponification reaction
in water they form a cluster due to hydrophobic part
CH3COOCH3 + NaOH
of molecules orient themselves away from water.
CH3COONa + CH3OH
So they arrange towards inside of the cluster while
hydrophilic part remain outside of cluster. (3) Combustion reaction
No, micelles will not be formed in alcohol. Soap in
CH4 + 2O2 CO2 + 2H2O
form of micelles is able to clean because the oily dirt
will be collected in centre of micelle which is rinsed 165. Identify the compounds ‘A’ to ‘E’ in the following
away by water. sequence:
KMNO 4 /KOH
162. a.Differentiate between soap and detergent. a. CH3CH2OH dil. HCl
A + H2O
b. Explain why, soaps form scum with water whereas b. CH3CH2OH + A B + H2O
Conc. H 2 SO 4
D
detergent do not.
c. B + NaOH C + CH3CH2OH
Ans : [CBSE 2015]
d. A + NaHCO3 C + D + H2O
e. CH3CH2OH + E CH3CH2ONa + H2
Soap Detergent
Ans : [CBSE 2013]
1. Sodium salts of fatty Sodium salts of KMNO 4 /KOH
acids. sulphonic acids. a. CH3CH2OH dil. HCl
CH3COOH + H2O
‘A’
2. They do not work They work well even
Conc. H 2 SO 4
well with hard water. with hard water. b. CH3CH2OH + CH3COOH D
‘A’
b. Sodium salts of fatty acids (soaps) react with CH3COOCH2CH3 + H2O
Ca2+ and Mg2+ ions in hard water to form insoluble ‘B’

salts called scum. Detergents form soluble salts c. CH3COOCH2CH3 + NaOH

‘B’
with Ca2+ and Mg2+.
CH3COONa + CH3CH2OH
‘C’
163. a.How is vinegar made?
d. CH3COOH + NaHCO3
b. What is glacial acetic acid? What is its melting
CH3COONa + CO2 + H2O
point? ‘C’ ‘D’
c. Why are carboxylic acids called weak acids? e. 2CH3CH2OH + 2Na 2CH3CH2ONa + H2
d. Write the name and formula of compounds ‘E’

formed when the ester CH3COOC2H5 undergoes A is CH3COOH, ‘B’ is CH3COOCH2CH3, *C’ is
saponification. CH3COONa, ‘D’ is CO2, ‘E’ is Na (Sodium metal).
Ans : [CBSE 2014, 2013]
166. An organic compound “X’ on heating with cone.
a. Vinegar is 5-8% solution of acetic acid (Ethanoic H2SO4 forms a compound ‘Y’ which on addition of
acid) in water. It can be made by fermentation of one molecule of hydrogen in the presence of nickel
ethanol in presence of oxygen. forms a compound ‘Z’. One molecule of compound
b. Glacial acetic is pure (100%) acetic acid. Its ‘Z’ on combustion forms two molecules of CO2 and
melting point is 290 K. three molecules of H2O. Identify giving reasons the
c. They do not ionise completely in aqueous solution. compounds X’, ‘Y’ and ‘Z’. Write the chemical
d. CH3COOC2H5 + NaOH equations for all the chemical reactions involved.
CH3COONa + C2H5OH Ans : [CBSE 2013]
Sodium ethanoate Ethanol Conc. H 2 SO 4
CH3CH2OH heat
CH2 = CH2 + H2O
‘X’ ‘Y’
164. a. How will you bring out following reactions? Write Ni
CH2 = CH2 + H2 CH3 – CH3
‘Y’ ‘Z’
 C2H6 + (7/2)O2 2CO2 + 3H2O Ethanol Ethanoic acid
‘Z’ on combustion gives 2CO2 and 3H2O so hydrocarbon
(a) Physical taste: It is It is solid below 290
‘Z’ must be ethane. “Y’ on addition of H2 gives ethane
liquid. K
so ‘Y’ must be ethene. “X’ in presence of cone. H2SO4
dehydrates to ethene i.e., ‘X’ is ethanol.
(b) Taste: It has It has sour taste.
167. List in tabular form three physical and two chemical burning taste.
properties on the basis of which ethanol and ethanoic
acid can be differentiated. (c) NaHCO3 test It does It liberates CO2 gas.
not react.
Ans : [CBSE 2012]
(d) Ester test: It reacts It reacts with alcohol
Ethanol Ethanoic acid with carboxylic acid to form pleasant to
to form easter form fruity smelling
Physical Properties esters.
1. It has Specific smell It has vinegar (ii)
like smell. CH3CH2OH +
Conc. H 2 SO 4
CH2=CH2 + H2O
443 K
2. It has burnnrg It has sour taste
taste 170. Give reasons for the following:
a. Element carbon forms compound mainly by
covalent bonding.
3. Pure ethanol is liquid Pure acetic b. Diamond has high melting point.
of room temprature. acid is solid c. Graphite is good conductor of electricity.
below 290 K. d. Acetylene bums with sooty flame.
Chemical Properties e. Kerosene does not decolourise bromine water
whereas cooking oil does.
4. It does not It turn-s blue
change colour litmus red. Ans : [CBSE 2011]
of litmus a. It is because carbon can neither lose 4 electrons
nor gain 4 electrons. It can share four electrons to
5. It does not react with It liberstes
form covalent bonds.
NaHCO3 CO2 with
b. Diamond has strong C—C bonds and compact 3-D
NaHC03.
structure in which one carbon atom is covalently
bonded to other four carbon atoms therefore, has
168. What are detergents chemically? List two merits and
high melting point.
two demerits of using detergents for cleansing. State c. In graphite, one carbon atom is bonded to other
the reason for the suitability of detergents for washing three carbon atoms. Remaining one electron on
even in case of water having calcium and magnesium each carbon is free to move due to which graphite
ions. conducts electricity.
Ans : [CBSE 2012] d. Acetylene has high carbon content, therefore,
Detergents are sodium or potassium salts of sulphonic partial oxidation causes it to bum with sooty or
acids of benzene or sulphates of unsaturated smoky flame.
hydrocarbons like alkenes with —SO3Na or —SO4Na e. Kerosene is a saturated compound, therefore,
group. does not decolourise bromine water.
Merits:
They are more effective than soaps.
They work well even with hard water.
Demerits:
a. They are expensive.
b. Some of them create water pollution.

169. a.In a tabular form, differentiate between ethanol

and ethanoic acid under the following heads:
(i) Physical state
(ii) Taste
(iii) NaHCO3 test
(iv) Ester test
b. Write a chemical reaction to show dehydration of
ethanol.
Ans : [CBSE 2011]
(i)