Carbon and its Compounds
These are
the solutions of chapter 4 Carbon and its compounds of class 10 science of RBSE
(Rajasthan education board). These solutions have been prepared by a well
experienced faculty.
.jpg "RBSE Solutions for Class10 Science Chapter 4 Carbon and its Compounds")
If you
are preparing for RBSE class 10 board exams, then these solutions of intext and
end exercise questions will help you a lot.
|
Board |
RBSE |
|
Subject |
Science |
|
Chapter |
Carbon and its Compounds |
|
No. of Intext questions |
13 |
|
No. of End exercise questions |
15 |
|
Prescribed Book |
NCERT Science |
Answers of Questions on Page 61
Q.1 What would be
electron dot structure of carbon dioxide which has the formula CO2.?
Answer Electron dot structure of CO2
is as follows:
Q.2 What would be the
electron dot structure of a molecule of sulphur which is made of eight atoms of
sulphur? [Hint: The eight atoms of sulphur are joined together in the form of a
ring].
Answer
Answers of Questions on Page 68
Q.1 How many structural isomers can you draw for pentane?
Answer
We can draw three structural isomers for
pentane.
Q.2 What are two
properties of carbon which lead to the huge number of carbon compounds we see
around us?
Answer
(i).Catenation –The ability of carbon atom to form bonds with other atoms of carbon is called catenation. So carbon atoms join with one another to form long chain.
(ii). Tetravalency–Carbon is a
tetravalent element. It has four free electrons in its outermost shell so
carbon atom share its four electron with other carbon atoms, oxygen , hydrogen
etc. that’s why carbon is capable
of bonding with four other atoms
Q.3 What will be the
formula and electron dot structure of cyclopentane?
Answer Formula C5H10
Q.4 Draw the structures for the following :
(i) Ethanoic acid
(ii) Brompentane(all possible isomers)
(iii) Butanone
(iv) Hexanal
Answer
(i) Ethanoic
acid
(ii). Bromopentane
(iii). Butanone
(iv).
Hexanal
Q.5 How would you name
the following compounds?
Answer
(i) Bromo ethane
(ii) Methanal
(ii) Hexyne
Answers of Questions on Page 74
Q.1 Conversion of ethanoic acid from ethanol is called
oxidation reaction. Why?
Answer
Conversion of ethanoic acid from ethanol is called oxidation
reaction because oxygen is added to ethanol. It is an oxidation
reaction.
Q.2 A mixture of oxygen and ethyne is burnt for welding. Can
you tell why a mixture of ethyne and air
is not used?
Answer
When Ethyne is burnt with oxygen, it gives a clean flame
with high temperature because of complete combustion.
That’s why this oxy-acetylene flame is used for welding. This
is the reason why a mixture of ethyne and air is not used.
But when Ethyne is burnt in
air, it gives a sooty flame due to incomplete
combustion. Its incomplete combustion takes place in air and carbon particles
remain unburnt. That’s why a mixture of Ethyne and air is not used for welding.
Answers of Questions on Page 75
Q.1 How would you
distinguish experimentally between an alcohol and a carboxylic acid?
Answer
We can distinguish between an alcohol and a carboxylic acid
on the basis of their
chemical reactions
(i)Add some litmus solution to both the
test tubes containing ethanol and ethanoic acid. Colour of litmus solution in
the test tune containing Ethanoic acid [Carboxylic acid] gets changed to red,
but no change in colour in test tube containing ethanol.
Ethanoic acid + litmus solution → Red litmus solution
Ethanol +
litmus solution → no colour change
(ii)Add sodium hydrogen carbonate or
sodium carbonate to both the test tubes containing ethanol and carboxylic acid.
Formation of carbon dioxide gas with effervescence indicates the presence of
carboxylic acid. But ethanol does not react with carbonates and hydrogen
carbonates
Ethanoic acid + metal
carbonate/ metal hydrogen carbonate → salt + water + carbon di oxide
Q.2 What are oxidising
agents?
Answer
The substances that oxidise the other
substance are called oxidising agents.
Answers of Questions on Page 76
Q.1 Would you be able
to check if water is hard by using a detergent?
Answer
Detergents are ammonium or sulphonate salts of long chain
carboxylic acids and they do not react
with calcium and magnesium ions present in hard water to form scum so detergents form lather effectively both in soft and hard water.
That’s why detergents can’t be used in checking whether water is hard or soft.
Q.2 People use a variety of methods to wash clothes, usually
after adding the soap, they ‘beat’ the clothes on a stone, or
beat it with a paddle, scrub with a brush or the mixture is
agitated in a washing machine. Why is agitation necessary to
get
clean clothes?
Answer
A soap molecule has two parts namely hydrophobic and
hydrophilic .These two ends of soap molecule attaché with
dirt or grease particles to form micelles. The Micelles entrap
oil or grease molecules and attachment of dirt particles
become weak. To remove the dirt particles agitation is
necessary.
Answers of EXERCISE Questions
Q.1 Ethane, with the
molecular formula – C2H6 – has
(a) 6 covalent bonds
(b) 7 covalent bonds
(c) 8 covalent bonds
(d) 9 covalent bonds
Ans. (b) 7
covalent bonds
Q.2 Butanone is a
four-carbon compound with the functional group
(a) carboxylic acid
(b) aldehyde
(c) ketone
(d) alcohol
Ans. (c) ketone
Q.3 While cooking, if
the bottom of the vessel is getting blackened on the side, it means that
(a) the
food is not cooked completely
(b) the
fuel is not burning completely
(c) the
fuel is wet
(d) the
fuel is burning completely
Ans. (b) the
fuel is not burning completely
Q.4 Explain the nature
of the covalent bond using the bond formation in CH3Cl.
Ans.
Electronic configuration of Cl is 2, 8, 7 and it requires 1 electron to
complete its octet and each hydrogen requires 1 electron to complete its
doublet. So the following electron dot structure is given for CH3Cl.
So C forms 4 single covalent bonds, 3 with 3 H atoms and one with Cl atom.
Q.5 Draw the electron
dot structure for
(a) Ethanoic acid
(b) H2S
(c) Propanone
(d) F2
Answer
(a) Ethanoic acid
(b)
H2S
(c)
Propanone
(d). F2
Q.6 What is homologous
series?
Answer
The series of organic compounds having different numbers of
carbon atoms but contain the same functional group. The two
adjacent members have a difference of CH2 unit, is called
homologous series.
The
general formula of this series is CnH2n +2.
Methan `CH_4`
Ethan `CH_3CH_3`
Propane `CH_2CH_2CH_3`
Butane `CH_3CH_2CH_2CH_3`
Q.7 How can ethanol and
ethanoic acid be differentiated on the basis of their physical and chemical
properties?
Answer
On the basis of physical and chemical properties, ethanol and
ethanoic acid can be distinguish as follows;
1. Ethanol is a liquid at room temperature with a pleasant
odour while ethanoic acid hasvinegar-like smell. The
meltingpoint of ethanoic acid is 290K.,it freezes during
winters.
2. Ethanoic acid changes blue litmus solution to red, while
ethanol shows no change in litmus solution.
3.On adding sodium carbonate or sodium hydrogen carbonate,
ethanoic acid produces carbon dioxide gas which turns lime
water milky, while no reaction takes place with ethanol.
Q.8 Why micelle formation
does take place when soap is added to water? Will a micelle be formed in other
solvents like ethanol also.
Answer
A soap is a sodium or potassium salt of long chain fatty acids.
It has one polar end and one non-polar end.
(i) a long hydrocarbon part and
(ii) a short ionic part – COONa+ group.
Long hydrocarbon part is hydrophobic (water repelling) part
while COONa+ is hydrophilic (water attracting) part. When
soap is added to water, soap molecules arrange themselves in
a cluster to keep the non-polar portion out of water such that
the non-polar ends are in the interior of the cluster and the
polar ends are on the surface of the cluster. This formation is
called micelle. Micelle will not be formed in other solvents
such as ethanol.
Q.9 Why are carbon and
its compounds are used as fuels for most applications?
Answer
Most of the carbon compounds give a lot
of heat and light when burnt in air.that’swhy
the carbon compounds are used as
a fuel.
(i) `C+O_2 →CO_2 + Heat + Light`
(ii) `CH_4 + 4O_2 →CO_2 + 2H_2O +Heat +Light`
Q.10 Explain the
formation of scum when hard water is treated with soap?
Answer
Hard water contains calcium and magnesium salts. A soap is a
sodium or potassium salt of long chain fatty acids. When soap
is added to hard water, calcium and magnesium ions present
in water displace sodium or potassium ions from the soap
molecules forming an insoluble
substance called scum.
Q.11What change
will you observe if you test soap with litmus paper (red or blue)?
Answer
Soap is basic in nature. When soap is tested with litmus paper,
it will affect the colour of litmus paper.It will turn red litmus
blue. However, the colour of blue litmus will remain blue.
Q.12What is
hydrogenation? What is the industrial application?
Answer
Hydrogenation – In this process hydrogen is added to
unsaturated hydrocarbons.
Industrial use of hydrogenation - Vegetable oil contains
unsaturated hydrocarbon chain. When hydrogen is passed
through them in the presence of palladium and nickel
catalyststo give saturated hydrocarbons.
Q.13 Which of the
followings hydrocarbons undergo addition reactions C2H6,
CH8, C3H6, C2H2 and CH4?
Answer
Hydrocarbons C3H6, C2H2 and CH4 will undergo addition
reactions,
because they are unsaturated hydrocarbons.
C2H2 +
H2 →C2H6
Q.14 Give a test
that can be used to differentiate chemically between butter and cooking oil.
Answer
Cooking oil contains unsaturated fatty acid. That is why it can
be hydrogenated to saturated fats.On the other hand butter
contains saturated fats. Therefore, it cannot be hydrogenated.
Q.15 Explain the
mechanism of the cleaning action of soaps.
Answer
A soap molecule is made up two parts- i). long hydrocarbon
chain and ii). Short ionic part short ionic part –
COONa+group.Long hydrocarbon part is hydrophobic (water
repelling) part while COONa+ is hydrophilic (water attracting)
part. When soap is added to water, soap molecules arrange
themselves in a cluster to keep the non-polar portion out of
water such that the non-polar ends are in the interior of the
cluster and the polar ends are on the surface of the cluster.
This cluster is called micelle. The dirt and grease particles get
entrapped in micelle and are removed when treated with
water.
Related Topics
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1 | |
2 | |
3 | |
4 | |
5 | |
6 | |
7 | How do Organisms Reproduce? |
8 | Heredity |
9 | Light – Reflection and Refraction |
10 | The Human Eye and the Colourful World |
11 | Electricity |
12 | Magnetic Effects of Electric Current |
13 | Our Environment |
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