Carbon And It's Compounds
Class: 10 | Chapter: 4
Intext Questions with Answer
1. What would be the electron dot structure of carbon dioxide which has the formula CO2 ?Ans. Electron dot structure of CO2 :
2. What would be electron dot structure of sulphur which is made up of eight atoms of sulphur.
Ans. Electron dot structure of Sulphur :
3. How many structural isomers can you draw for pentane ?
Ans. Pentane has three isomers. These are n - pentane, iso - pentane,neo - pentane.
Stuctural formula :
4. What are the two properties of carbon which lead to the huge number of carbon compounds we see around us ?
Ans. Carbons forms a huge number of carbon compounds due to its tetravalency, self linking property ( catenation) and tendency to form multiple bonds.
5. What will be the formula and electron dot structure of cyclopentane ?
Ans. Formula Of Cyclopentane : C5H10
Electron dot structure of cyclopentane :
6. Draw the structures for the following compounds :
(i) Ethanoic acid
(ii) Bromopentane
(iii) Butanone
(iv) Hexanal
Ans.
7. How would you name the following compounds ?
Ans. (i) Bromoethane
(ii) Methanal
(iii) Hexyne
8. A mixture of oxygen and ethyne is burnt for welding. Can you tell why a mixture of ethyne and air is not used ?
Ans. For welding purposes, a high temperature is needed and it is possible in complete combustion of ethyne. Air has only about 21 % of oxygen so, it is necessary to use oxygen gas instead of air to get more percentage of oxygen and for occurrance of complete combustion.
9. How would you distinguish experimentally between an alcohol and a carboxylic acid ?
Ans. 1.Blue Litmus Test : Alcohol will not any colour change but carboxylic acid will changes to red.
2. NaHCO3 Test : Brisk effervescences appear in case of carboxylic acids and alcohols don't show any change.
3. Smell Test : Alcohols have spirit like smell and carboxyluc acids give pungent smell.
10. What are oxidising agents ?
Ans. Oxidising agents : The chemical substances which provide oxygen to others or can accept electrons from others. Example : Conc. H2SO4, Niteic acid, Potassium permanganate etc.
11. Would you be able to check if water is hard by using a detergent ?
Ans. No, it's not possible becouse detergents can work in hard water also.
12. 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. It helps in separation of dust and dirt particles from the surface of clothes.
Exercise Questions with Answer
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. (a) 6 covalent bonds
2. Butanone is a four-carbon compound with the functional group
(a) carboxylic acid
(b) aldehyde
(c) ketone
(d) alcohol
Ans. (c) ketone
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) the fuel is not burning completely
4. Explain the nature of the covalent bond using the bond formation in CH3Cl.
Ans. In CH3Cl, there are 3 C- H bonds and one C - Cl bond. Covalent bonds can be polar and non - polar. C- H bonds are non - polar becouse both atoms have no significant electronegativity difference. But in C - Cl bond, Cl is more electronegarive than C. So, electrons of this bonds will be attracted towards Cl and hence it is a polar bond.
5. Draw the electron dot structures for
(a) ethanoic acid
(b) propanone
(c) H2S
(d) F2.
Ans. (a)
Ans. Homologous series : A sequence of organic compounds having a particular functionsl group and have a common difference of -CH2 . For example in alkanes, methane ( CH4) , ethane ( C2H6) and propane ( C3H8 ) are the members and they have a difference of - CH2.
7. How can ethanol and ethanoic acid he differentiated on the basis of their physical and chemical properties ?
Ans. Physical properties :
1. Smell : Ethanol gives spirit like smell and ethanoic acid has pungent smell.
2. By reducing the temperature, ethanol doesn't freeze but ethanoic acid freezes to give ice like crystals.
Chemical properties : 1.Blue Litmus Test : Ethanol will not any colour change but ethanoic acid will changes to red.
2. NaHCO3 Test : Brisk effervescences appear in case of ethanoic acids and ethanol doesn't show any change.
8. Why does micelle formation take place when soap is added to water ? Will a micell be formed in other solvents such as ethanol also ?
Ans. Soaps have general formula RCOO-Na+. When we put dirty colth in soap solution, R part attches with oil and dirt and COO- directs towards water. The sodium ions arrange around - COO- ions. Now, this negatively charged micelle traps the oil and dirt. Yes, it can be formed in other solvents also.
9. Why are carbon and its compounds used as fuels for most applications ?
Ans. Carbon And it's compounds have high calorific value. When we burn them, they give high energy, light with no smoke. That's why they are used as fuel.
10. Explain the formation of scum when hard water is treated with soap.
Ans. Hard water has calcium and magnesium ions in it. When these ions react with soap , they form insoluble calcium and magnesium fatty acid salts which appear white curdy precipitate. This is called scum.
11. What change will you observe if you test soap with litmus paper (red and blue)?
Ans. Soap are basic in nature so, they will change only red litmus to blue. There will be no change in colour with blue litmus paper.
12. What is hydrogenation ? What is its industrial application ?
Ans. Hydrogenation : The addition of hydrogen to a unsaturated conpound is called hydrogenation reaction.
Industrial Application : it is used to make vegetable ghee from vegetable oils. Here vegetable oils like groundnut oil and cotton seed oils are converted into vegetable ghee in presence ofccatalysts like nickel.
13. Which of the following hydrocarbons undergo addition reactions :
C2H6, C3H8, C3H6, C2H2 and CH4
Ans. Unsaturated compounds undergo addition reactions. So, C3H6, C2H2 will give addition reactions.
14. Give a test that can be used to differentiate chemically between butter and cooking oil.
Ans. Chemically butter is saturated and cooking oil is unsaturated in nature. So, we can confirm it by alkaline KMnO4 or Bromine water test. Alkaline KMnO4 loses its pink colour in presence of cooking oil whereas in case of butter it remains. In the same way ,brown colour of bromine water also goes away in cooking oil.
15. Explain the mechanism of the cleaning action of soaps.
Ans. Soaps have general formula RCOO-Na+. When we put dirty colth in soap solution, R part attches with oil and dirt and COO- directs towards water.The sodium ions arrange around - COO- ions. Now, this negatively charged micelles trap the oil and dirt and repel each other to get separated from cloth.