These arethe solutions of chapter 4 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. Before solving these questions, you can revise the chapter from Quick Revision Notes and practice with MCQs of Chapter 4 for better understanding.
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Board |
RBSE |
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Subject |
Science |
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Chapter |
Carbon and its Compounds |
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No. of Intext questions |
13 |
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No. of End exercise questions |
15 |
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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 twoproperties of carbon which lead to the huge number of carbon compounds we seearound us?
Answer
(i).Catenation –The ability ofcarbon 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) Bromo pentane(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. Canyou tell why a mixture of ethyne and air is not used?
Answer
When Ethyne is burnt with oxygen, it gives a clean flamewith 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 homologousseries?
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 CH4
Ethan CH3CH3
Propane CH2CH2CH3
Butane CH3CH2CH2CH3
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 has vinegar-like smell. The melting point 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) ashort 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’s why the carbon compounds are used as a fuel.
(i) C+O2 →CO2 + Heat + Light
(ii) CH4 + 4O2 →CO2 + 2H2O +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 catalysts to 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.
RBSE Class 10 Science Questions Answers
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