NCERT Solutions for Class 10 Science Chapter 4 Carbon and Its Compounds

NCERT Solutions For Chapter 4 Class 10 Science Carbon and Its Compounds : Class 10 is the first stepping stone for a student in the competitive world. With the introduction of the CBSE Board Exam for class 10 a few years back, this has become an important gateway for a student as based on the results of class 10th a student selects his future stream of Science, Commerce, or Arts.

Takshila Learning provides you with detailed and well explained NCERT Solutions for Class 10 of each chapter of each subject for NCERT Class 10. These NCERT Solutions help you to easily understand every concept so that you can score high in your CBSE Class 10 Board Exams.

Below you can find the NCERT solution for Class 10th Science. You can get a Solution for the all-important question of “Metals and non metals”

Ques 1: What would be the electron dot structure of carbon dioxide which has the formula CO₂?

Ans: Electron dot structure of CO_{2 –}

 

 

Ques 2: What would be the electron dot structure of a molecule of sulphur which is made up of eight atoms of sulphur? (Hint − the eight atoms of sulphur are joined together in the form of a ring.

Ans: Electron dot structure of a sulphur molecule

 

 

 

 

 

Pg No. 68

 

Ques 1: How many structural isomers can you draw for pentane?

Ans: Three structural isomers are possible for pentane.

 

 

Ques 2: What are the two properties of carbon which lead to the huge number of carbon compounds we see around us?

Ans: The two highlights of carbon that offer ascent to an enormous number of mixes are as per the following:

(I) Catenation − It is the capacity to shape bonds with different iotas of carbon.

(ii) Tetra valency − With the valency of four, carbon is equipped for holding with four different iotas.

 

 

Ques 3: What will be the formula and electron dot structure of cyclopentane?

Ans: The formula for cyclopentane is C₅H₁₀. Its electron dot structure is given below.

 

 

Ques 4: Draw the structures for the following compounds.

• Ethanoic acid
• Bromopentane*
• Butanone
• Hexanal

*Are structural isomers possible for bromopentane?

 

Ans: (i)

The structure of ethanoic acid:

 

(ii) Structure of Bromopentane:

 

 

 

(iii) Structure of butanone:

 

 

(iv) Structure of hexanal:

 

 

 

Yes, there are many structural isomers are possible for bromopentane. Among them, the structure of three isomers is given below:

 

 

 

 

 

Ques 5: How would you name the following compounds?

 

(i) CH₃ – CH₂ – Br

           

             H

               l

(ii)  H – C  = O

 

(iii)

 

 

 

Ans:     (i) Bromo ethane

 

(ii) Methanal (formaldehyde)

 

(iii) Hexyne

 

 

 

 

Pg No. 71

 

Ques 1: Why is the conversion of ethanol to ethanoic acid an oxidation reaction?

 

Ans: Since the conversion of ethanol to ethanoic acid involves the addition of oxygen to ethanol, it is an oxidation reaction.

 

 

Ques 2: A mixture of oxygen and ethyne is burnt for welding. Can you tell why a mixture of ethyne and air is not used?

Ans: When ethyne is burnt in air, it gives a sooty flame. This is due to incomplete combustion caused by limited supply of air. However, if ethyne is burnt with oxygen, it gives a clean flame with temperature 3000°C because of complete combustion. This oxy-acetylene flame is used for welding. It is not possible to attain such a high temperature without mixing oxygen. This is the reason why a mixture of ethyne and air is not used.

 

 

 

Pg No. 74

 

Ques 1: How would you distinguish experimentally between an alcohol and a carboxylic acid?

Ans:

We can distinguish between an alcohol and a carboxylic acid on the basis of their reaction with carbonates and hydrogen carbonates. Acid reacts with carbonate and hydrogen carbonate to evolve CO2 gas that turns lime water milky.

Alcohols, on the other hand, do not react with carbonates and hydrogen carbonates.

 

 

 

Ques 2: What are oxidising agents?

Ans: Some substances such as alkaline potassium permanganate and acidified potassium dichromate are capable of adding oxygen to others. These are known as oxidising agents.

 

 

 

Pg No. 76

 

Ques 1: Would you be able to check if water is hard by using a detergent?

Ans: Detergents are ammonium or sulphonate salts of long chain carboxylic acids. Unlike soap, they do not react with calcium and magnesium ions present in hard water to form scum. They give a good amount of lather irrespective of whether the water is hard or soft. This means that detergents can be used in both soft and hard water. Therefore, it cannot be used to check whether the water is hard or not.

 

 

Ques 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?

Ans: A soap molecule has two parts namely hydrophobic and hydrophilic. With the help of these, it attaches to the grease or dirt particle and forms a cluster called micelle. These micelles remain suspended as a colloid. To remove these micelles (entrapping the dirt), it is necessary to agitate clothes.

 

Pg No. 77

 

Q1. 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) Ethane has 7 covalent bonds.

 

Ques 2: Butanone is a four-carbon compound with the functional group

(a) carboxylic acid.

(b) aldehyde.

(c) ketone.

(d) alcohol.

 

Ans: (c) The functional group of butanone is ketone.

 

Ques 3: While cooking, if the bottom of the vessel is getting blackened on the outside, 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) While cooking, on the off chance that the base of the vessel is getting darkened outwardly, at that point it implies that the fuel isn’t consuming totally.

 

 

Ques 4: Explain the nature of the covalent bond using the bond formation in CH₃Cl.

Ans: Carbon can neither lose four of its electrons nor increase four electrons as both the procedures require additional measure of vitality and would make the framework temperamental. In this way, it finishes its octet by offering its four electrons to other carbon molecules or with particles of different components. The bonds that are framed by sharing electrons are known as covalent bonds. In covalent holding, both the iotas share the valence electrons, i.e., the mutual electrons have a place with the valence shells of both the particles.

Here, carbon requires 4 electrons to complete its octet, while each hydrogen atom requires one electron to complete its duplet. Also, chlorine requires an electron to complete the octet. Therefore, all of these share the electrons and as a result, carbon forms 3 bonds with hydrogen and one with chlorine.

 

 

Ques 5: Draw the electron dot structures for

(a) ethanoic acid.

(b) H₂S.

(c) propanone.

(d) F₂.

 

Ans:

 

 

 

Ques 6: What is a homologous series? Explain with an example.

Ans: A homologous series is a series of carbon compounds that have different numbers of carbon atoms but contain the same functional group.

For example, methane, ethane, propane, butane, etc. are all part of the alkane homologous series. The general formula of this series is CnH2n+2.

Methane – CH₄

Ethane – CH₃CH₃

Propane – CH₃CH₂CH₃

Butane – CH₃­CH₂CH₂CH₃

 

It can be noticed that there is a difference of −CH₂ unit between each successive compound.

 

 

Ques 7: How can ethanol and ethanoic acid be differentiated on the basis of their physical and chemical properties?

Ans: 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 17°C. This is below room temperature and hence, it freezes during winters.

Ethanoic acid reacts with metal carbonates and metal hydrogencarbonates to form salt, water, and carbon dioxide gas while ethanol does not react with them.

 

 

Ques 8: Why does micelle formation take place when soap is added to water? Will a micelle be formed in other solvents such as ethanol also?

Ans: A soap is a sodium or potassium salt of long chain fatty acids. It has one polar end and one non-polar end. The polar end is hydrophilic in nature i.e., this end is attracted towards water. The non-polar end is hydrophobic but lipophilic, i.e., it is attracted towards hydrocarbons. 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. Since the dirt present on clothes is organic in nature and insoluble in water, the hydrophobic ends of the clusters attach themselves to the dirt. This cluster formation in which the dirt is entrapped is the micelle.

 

 

Micelle formation does not occur in alcohol because the alkyl chain of soap becomes soluble in alcohol.

 

 

Ques 9: Why are carbon and its compounds used as fuels for most applications?

Ans: Most of the carbon compounds give a lot of heat and light when burnt in air. Saturated hydrocarbons burn with a clean flame and no smoke is produced. The carbon compounds, used as a fuel, have high calorific values. Therefore, carbon and its compounds are used as fuels for most applications.

 

 

Ques 10: Explain the formation of scum when hard water is treated with soap.

Ans: Soap does not work properly when the water is hard. A soap is a sodium or potassium salt of long chain fatty acids. Hard water contains salts of calcium and magnesium. 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. A lot of soap is wasted in the process.

 

 

Ques 11: What change will you observe if you test soap with litmus paper (red and blue)?

Ans: Since soap is basic in nature, it will turn red litmus blue. However, the colour of blue litmus will remain blue.

 

 

Ques 12: What is hydrogenation? What is its industrial application?

Ans: Hydrogenation is the process of addition of hydrogen. Unsaturated hydrocarbons are added with hydrogen in the presence of palladium and nickel catalysts to give saturated hydrocarbons.

 

This reaction is applied in the hydrogenation of vegetables oils, which contain long chains of unsaturated carbons.

 

 

 

Ques 13: Which of the following hydrocarbons undergo addition reactions?

C₂H₆, C₃H₈, C₃H₆, C₂H₂ and CH₄.

Ans: Unsaturated hydrocarbons experience expansion responses. Being unsaturated hydrocarbons, C₃H₆, and C₂H₂ experience expansion responses.

 

 

 

Ques 14: Give a test that can be used to differentiate chemically between butter and cooking oil.

Ans: Butter contains immersed fats. In this manner, it can’t be hydrogenated. Then again, oil has unsaturated fats. That is the reason it tends to be hydrogenated to soaked fats (solids).

 

 

Ques 15: Explain the mechanism of the cleaning action of soaps.

Ans: Cleansing action of soaps:

The dirt present on garments is natural and insoluble in water. In this way, it can’t be expelled by just washing with water. At the point when cleanser is broken up in water, its hydrophobic finishes append themselves to the earth and expel it from the fabric. At that point, the atoms of cleanser mastermind themselves in micelle development and trap the soil at the focal point of the group. These micelles stay suspended in the water. Henceforth,

the residue particles are effectively flushed away by water.

 

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