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Chapter Review:

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• The earth’s crust has only 0.02% carbon in the form of minerals (like carbonates, hydrogencarbonates, coal and petroleum) and the atmosphere has 0.03% of carbon dioxide.
• Ionic compounds have high melting and boiling points and conduct electricity in solution or in the molten state.
• The atomic number of chlorine is 17.
• Such bonds which are formed by the sharing of an electron pair
  between two atoms are known as covalent bonds.
• Covalent bond molecules are seen to have strong bonds within the molecule, but intermolecular forces are small.
• Carbon has three allotropes (i) graphite (ii) diamond (iii) C-60
  Buckminsterfullerene.
• Diamond is the hardest substance known while graphite is smooth and slippery. Graphite is also a very good conductor of electricity.
• The formation of covalent bonds by the sharing of electrons in various elements and compounds.
• Compounds of carbon, which are linked by only single bonds between the carbon atoms are called saturated compounds.
• Compounds of carbon having double or triple bonds between their
  carbon atoms are called unsaturated compounds.
• The two characteristic features seen in carbon, that is, tetravalency and catenation.
• Compound of carbon and hydrogen has the formula C₂H_​4 and is called ethene.
• Compound of hydrogen and carbon has the formula C₂H₂ and is called ethyne.
• Such compounds with identical molecular formula but different structures are called structural isomers.
• All these carbon compounds which contain just carbon and hydrogen
  are called hydrocarbons.
• The saturated hydrocarbons are called alkanes.
• The unsaturated hydrocarbons which contain one or more double bonds are called alkenes.
• Those containing one or more triple bonds are called alkynes.
• Such a series of compounds in which the same functional group substitutes for hydrogen in a carbon chain is called a homologous series.
• Carbon allotropic forms, burns in oxygen to give carbon dioxide
  along with the release of heat and light.
• Unsaturated hydrocarbons add hydrogen in the presence of catalysts
  such as palladium or nickel to give saturated hydrocarbons.
• VegeTable oils generally have long unsaturated carbon chains while
  animal fats have saturated carbon chains.
• Ethanol is a liquid at room temperature.is commonly called alcohol and is the active ingredient of all alcoholic drinks. In addition, because it is a good solvent, it is also used in medicines such as tincture iodine, cough syrups, and many tonics.
• Ethanol produced for industrial use, it is made unfit for drinking by adding poisonous substances like methanol to it. Dyes are also added to colour the alcohol blue so that it can beidentified easily. This is called denatured alcohol.
• Ethanoic acid is commonly called acetic acid and belongs to a group of acids called carboxylic acids. 5-8% solution of acetic acid in water is called vinegar.
• Esters are sweet-smelling substances. These are used in making perfumes and as flavouring agents.
• Soaps are molecules in which the two ends have differing properties, one is hydrophilic,that is, it dissolves in water, while the other end is hydrophobic, that is, it dissolves in hydrocarbons.
• Detergents are generally ammonium or sulphonate salts of long chain
  carboxylic acids. The charged ends of these compounds do not form
  insoluble precipitates with the calcium and magnesium ions in hard
  water.

                            CH-4   Carbon and it’s compound

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Q1. What would be the electron dot structure of carbon dioxide which has the formula CO2?

Answer: 

 

 

Q2. 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.)

Answer:

Page no. 68 and 69 

Q1. How many structural isomers can you draw for pentane? 

Answer:

Q2. What are the two properties of carbon which lead to the huge number of carbon compounds we see around us?

Answer: Two properties of carbon :-

(i) The valency of carbon is four, so it joins with its own atoms with single, double, triple covalent bonds.

(ii) One carbon atom forms long catenation by forming bonds with other carbon atoms. The number of carbon compounds in it is very wide.

Q3. What will be the formula and electron dot structure of cyclopentane?

Answer:

Q4. Draw the structures for the following compounds.

(i) Ethanoic acid

(ii) Bromopentane

(iii) Butanone

(iv) Hexanal.

Are structural isomers possible for bromopentane?

Answer:

Page no. 68

Q1. Why is the conversion of ethanol to ethanoic acid an oxidation reaction?

Answer: Ethanoic + Oxygen → Ethanoic acid. In this way there is increase of oxygen and decrease of hydrogen and these reactions are called oxygen reactions.

Q2. A mixture of oxygen and ethyne is burnt for welding. Can you tell why a mixture of ethyne and air is not used?

Answer: Oxygen is not available in abundance in the air. Oxygen is required for complete combustion in welding, so only mixture of oxygen and ethene is used for welding. This mixture is called oxyacetylene gas.

Page no. 74

Q1. How would you distinguish experimentally between an alcohol and a carboxylic acid?

Answer: On reacting with sodium bicarbonate, the difference between the two is obtained. Sodium bicarbonate does not react with alcohol and does not produce gas. But CO₂ gas is emitted when ethanoic acid reacts.

Q2. What are oxidising agents?

Answer: Oxidizers are those substances which oxidise another substance and decompose itself. Example: KMnO₄

Page no. 76 

Q1. Would you be able to check if water is hard by using a detergent?

Answer: We cannot tell by using detergent whether water is hard or because they produce micelles (foam) in both the conditions.

Q2. 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: It reacts with soap scum to form a micelle structure. Oily scum tends to collect in the center of the micelles and stick to the clothes, so it is necessary to do this to clean it.

NCERT Solutions Exercise 

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Q1. Ethane, with the molecular formula C2H6 has

(a) 6 covalent bonds.

(b) 7 covalent bonds.

(c) 8 covalent bonds.

(d) 9 covalent bonds.

Answer: (b) 7 covalent bonds.

Q2. Butanone is a four-carbon compound with the functional group

(a) carboxylic acid.

(b) aldehyde.

(c) ketone.

(d) alcohol.

Answer: (c) ketone.

Q3. 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. 

Answer: (b) the fuel is not burning completely.

Q4. Explain the nature of the covalent bond using the bond formation in CH₃Cl.

Answer: In CH₃Cl, three hydrogen atoms are covalently bonded to one carbon atom. Similarly, there is a covalent bond between carbon chlorine as well.

Q5. Draw the electron dot structures for

(a) ethanoic acid.

(b) H2S.

(c) propanone.

(d) F2 .

Q6. What is an homologous series? Explain with an example.

Answer: A series of carbon compounds in which a type of functional group replaces hydrogen is called a homologous series.

For example - methane (CH₂), ethane (C₂H₆), propane (C₃H₈).

There is a difference of CH₂  unit among them. The general formula of alkenes can be written as C_nH_2n and N = 2,3,4.

Q7. How can ethanol and ethanoic acid be differentiated on the basis of their physical and chemical properties?

Answer: Physical Properties :-

(i) The smell of ethanol is characteristically alcoholic while that of ethanolic acid is strong.

(ii) The melting point of ethanol is 156K while the boiling point of ethanolic acid is 290K.

(iii) The boiling point of ethanol is 351K while that of ethanolic acid is 391K.

chemical properties :-

(i) Ethanol does not affect litmus paper whereas ethanol acid turns blue litmus paper red.

(ii) Ethanol does not react with sodium carbonate while ethanol acid reacts with sodium carbonate to produce CO2 gas.

Q8. Why does micelle formation take place when soap is added to water? Will a micelle be formed in other solvents such as ethanol also?

Answer: Micelles are formed when soap is added to water because soaps have two - a long hydrocarbon tail and a negative end. The tail is water resistant and the head watery. When it reacts with a polar solvent like water, the charged part causes the hydrophilic part, so they form clumps around the heads of the soap molecules and also form froth. Ethanol is not a polar solvent so it does not form lather with soap.

Q9. Why are carbon and its compounds used as fuels for most applications?

Answer: Carbon and its compounds generate a lot of heat as a result of combustion. Their combustion is easy to control and the ignition temperature is also normal, so their compound is used as fuel.

Q10. Explain the formation of scum when hard water is treated with soap.

Answer: The calcium and magnesium ions present in hard water react with soap to form insoluble salts. Hence, a white precipitate is formed.

2C₁₇H₃₅COONa + Mg²⁺ → (C₁₇H₃₅COO)_2Mg + 2Na⁺

Q11. What change will you observe if you test soap with litmus paper (red and blue)?

Answer: Soap is alkaline in nature hence it turns red litmus paper eco blue.

Q12. What is hydrogenation? What is its industrial application?

Answer: Unsaturated hydrocarbons combine with hydrogen to form saturated compounds. This process is called hydrogenation. This process is used to make ghee from oil. Vegetable oil +H₂

Q13. Which of the following hydrocarbons undergo addition  reactions: C₂H₆ , C₃H₈ , C₃H_{6 ,} C₂H₂ and CH₄.

Answer: Addition reaction will take place in C₂H₂ and C₃H₆ because they are unsaturated hydrocarbons

Q14. Give a test that can be used to differentiate chemically between butter and cooking oil.

Answer: Butter is saturated and edible oil is unsaturated hydrocarbon. These can be differentiated with the help of bromine water. Heat butter and oil. Now put some drops of bromine water in them. There is an organic compound in butter. Similarly, when bromine is added to oil, the color of the water turns off, so it is an unsaturated hydrocarbon.

Q15. Explain the mechanism of the cleaning action of soaps.

Answer: There are two ends in the direction of soap, one is anti-water and the other is burning. The anti-water end sticks to the dirt in the clothes, but the water-resistant end sticks to the water molecules. Due to this action, froth (micelle) is formed. In this lather, the soap molecules are arranged in a circular shape. Polar part CooNa+ .

Chapter-4, Carbon 

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Short Answers Questions: 

Q1: Why do carbon have the capacity to form the largest compound in the nature?

Ans: As it has an unique capacity to form the bond with others carbon atoms and due to nature of covalent bond.

Q2: What is catenation?

Ans: Carbon has the unique ability to form bonds with other atoms of
carbon, giving rise to large molecules. This property is called catenation. 

Q3: what is fermentation ?

Ans: The converting of difficult carbonic matters into the simple carbonic matters slowly in the presence of enzymes. This process is called fermentation.

Q4: Name that process by which we get ethanol from sugarcane and fruits juice.

Ans: Fermentation.

Q5:What is Ester? Write its uses.

Ans: The reaction by ethanol and ethanoic acid resulting forms the compound that is called Ester. 

Uses of Ester:

It is used in making perfumes and flavouring agents.  

Q6: What is Esterification reaction?

Ans: The reaction which gives Ester that is called estrification.

Q7: Define soapnification.

Ans: Ester reacts in the presence of an acid or a base to give back the alcohol and carboxylic acid this reaction is known as soapnification. 

Q8: write UPAC name of the simplest Aldehyde. What is its general name?

Ans: UPAC name of the simplest Aldehyde is methanol. Its general name is formaldehyde. 

Q9: What is formalin? Write its use.

Ans: 30 – 40 percent aqueous solution of formaldehyde is called as formalin. It is used in laboratory to preserve died sample of animals and its organs to keep for a long time.     

Q10: What is the nature of carboxylic group.

Ans: The nature of carboxylic group is acidic.

Q11: write the chemical formula of white led.

Ans: 2PbCIO₃Pb(OH)

Q12: Name the compound of carboxylic group which is used in manufacturing of white led.

Ans: Ethanoic Acid.

Q13: write three uses of Ethanoic Acid.

Ans: Three uses of Ethanoic Acid.

(i)  For preparing vinegar.

(ii)  As laboratory’s regent

(iii) Manufacturing of white led. 

Q14: Why does Ethanoic Acid dissolve in water in all ratios?

Ans: Ethanoic acid is an odorless and highly smelling liquid. Its melting point is 290 k . so it dissolve in water in all ratios.

Q15: write the name of that compound which is used for preservation of food materials and pickles.

Ans: Ethanoic Acid.

Q16: In presence of which enzyme is Ethanol oxidised in air?
Ans: Acitobactor Enzyme.

Q17: What is called the oxidised substance?

Ans: vinegar.

Q18: write the balance equation for this reaction.

Q19: Write a modern method for commercial manufacturing of Ethanoic Acid.

Ans: Ethanoic acid forms After reaction of methanol and carbon monoxide in presence of iodine radium.

Q20: what is chemical bond?

Ans: When one or more atoms share among themselves then they make a bond among their ions and they achieve the configuration of their nearest novel gas which is called chemical bond.

Q21: What is covalent bond?

Ans: The bonds which are formed by the sharing of an electron pair     between two atoms are known covalent bond.

Q22: What is structural isomer?

Ans: Such a compound which has identical (same) molecular formula but structure is difference is called structural isomer.

Q23: What is Hydro carbon?

Ans: All the compounds formed by carbon and hydrogen is called hydrocarbon.

Q24: What is Hetroatoms?

Ans: In a hydrocarbon chain, one or more hydrogens can be replaced by these elements, such that the valency of carbon remains satisfied. In such compounds, the element replacing hydrogen is referred to as a Hetroatoms.

Q25: write the name of two elements that show the characteristics of hetroatoms.

Ans: Chlorine and bromine. 

Q26: Which bonding is mostly shown by carbon in it's compound?

Q27: Why is hard water not suitable for washing clothes with soap? 

Q28: Why the saturated hydrocarbons give clean flame while unsaturaed carbon compounds give yellow flames? 

Q29: Why carbon compounds are poor conductor of electricity? 

Q30: What is catalyst? 

Q31: which acid is called glacial acid and why? 

Q32: Give regions, melting point and boiling point of carbon compounds are very low? 

Chapter-4, Carbon

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Long-Type Questions and Answers: 

Q1: Distinguish between saturated and unsaturated compound . which of them is more reactive.

Ans:

Saturated compound	unsaturated compound
it has single bond. There occurs substitution reaction in it. saturated compounds are normally not very reactive. Example: Alkanes.	it has double and triple bond. There occurs addition reaction in it. They are more reactive than the saturated carbon compounds. Examples: Alkenes,Alkynes

Unsaturated compound is more reactive than saturated compound.

Q2: What do you understand by functional group?

Ans: Functional group is a group of an atom or atoms in any carbonic compound which are bonded each other in special manner. That is generally region of chemical reactivity in carbonic atoms. Oxygen, chlorine, sulpher, nitrogen and other elements can be presence as a part of a functional group in carbonic compounds.

Ex. -    -CHO,      >C=O,       -OH,     -COOH   etc.

Q3: An organic Compound A is widely used as a preservative in pickles and has a molecular formula C₂ H₂ O_2. This compound reacts with ethanol to form a sweet smelling Compound B.

(a) Identify the Compound A and B.

(b) Write the chemical equation with ethanol to from compound B.

(c) How can we get compound A back from B.

(d) Name the process and write equations?.

(e) Which gas is produced when compound A reacts with washing Soda? Write the chemical equations?  

Ans: 

(a) A is Ethanoic acid or acetic acid and B is ester.

(b) The chemical equation with ethanol to form compound B is 

 

(c) Esters reat in the presence of an acid or base to give back the alcohol and Ethanoic acid (carboxylic acid). 

(d) This reaction (process) is called soapnification. The reaction equation is as

(e) CO₂ gas is produced, when the compound A (Ethanoic acid) reacts with washing soda (NaHCO₃). This reaction is as;

CH₃COOH + NaHCO₃ → CH₃COONa + H₂O + CO₂

Q4: How would you distinguish experimentally between alcohol and ethanoic acid.

Ans: 

Difference between ethanol and ethanoic acid

Ethanole	Ethanoic Acid
1. Ethanol is an alcohol with sweet smell. 2. It does not react with NaOH.  3. It reacts with alkaline KMnO4 to give ethanoic acid.  4. It does not effect on litmus paper.	1. Ethenoic acid is a acid with odorless heighly smelling. 2. It reacts with NaOH to give salt and water. 3. It does not react with alkaline KMnO4.  4. It turns blue litmus paper into red.

Q5: What happens when ethanol reacts with sodium. Write a chemical reaction.

Ans: When ethanol reacts with sodium produces sodium ethoxide and evolves hydrogen gas.

Equation of this reaction is as follows:

2Na + 2CH₃CH₂OH → 2CH₃CH₂O^–Na⁺ + H₂

Q6: What happens when ethanol is heated with.

(i) Alkaline KMnO₄

(ii) H₂SO₄ at 443 K

Write their equations.

Ans: 

(i) When ethanol is heated with alkaline KMnO₄ it gives carboxylic acids and water. Alkaline potassium permanganate or acidified potassium dichromate are oxidising alcohols to acids, that is, adding oxygen to the starting material. Hence they are known as oxidising agents.

Equation for this reaction: 

(ii) Heating ethanol at 443 K with excess concentrated sulphuric acid results in the dehydration of ethanol to give ethene-

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Q7: Give one example of addition reaction.

Ans:

 

Q8: Give one example of substitution reaction. 

Ans: CH₄ + Cl₂​ → CH₃Cl + HCl (in the presence of sunlight)

Q9: What are saturated and unsaturated carbon compounds ? Give one example each.

Ans: 

Saturated carbon compounds: The carbon compounds which forms single bond is called saturated hydro carbon. Example - Alkanes. 

Unsaturated carbon compounds: The carbon compounds which forms double and triple bond is called saturated hydro carbon. Example - Alkanes.

Q10: Draw structural isomers of C₄H₁₀.

Ans: structural isomers of C₄H₁₀

Q11: Name the following compounds

(i)  CH₃  - CH₂  -  Br

(ii) CH₃  - CH₂ - CHO 

Ans: 

(i) Bromo-Ethane,

(ii) Propanal, 

Q12: What is the region that saturated hydrocarbons give even sooty flame in incomplete combustion?

Ans: Saturated hydrocarbons will generally give a clean flame, but when a sooty deposit on the metal plate causes limiting supply of air results in incomplete combustion of even saturated hydrocarbons gives a sooty flame. 

Q13 – What is oxidation?

Ans – The reaction in which compounds like carbon can be easily oxidised on the combustion, this process is known as oxidation.

Q14 – Define Addition reaction?

Ans – The reaction in which adds the substances is known as Addition reaction. This reaction is commonly used in the hydrogenation of vegetable oils using a nickel catalyst.

Q15 – What are catalysts? Give its two examples.

Ans – Catalysts are substances that cause a reaction to occur or proceed at a different rate without the reaction itself being affected. Palladium or Nickel is catalysts.

Q16 - What is hydrogenation? What is its industrial application?

Ans - Unsaturated hydrocarbons add hydrogen in the presence of catalysts such as palladium or nickel to give saturated hydrocarbons is called hydrogenation. This reaction is commonly used in the hydrogenation of vegetable oils using a nickel catalyst in industry.

Q17 - What is a homologous series? Explain with an example.

Ans - a series of compounds in which the same functional group substitutes for hydrogen in a carbon chain is called a homologous series.

 For example, the chemical properties of CH3OH, C2H5OH, C3H7OH and C4H9OH are all very similar as these are from alcohol functional group. Thus, CH₃ – Cl, C₂H₅ – Cl, C₃H₇ – Cl, C₄ H₉ – Cl, and C₅ H₁₁ – Cl etc. are related to halogen functional group. 

Q18 - Why are carbon and its compounds used as fuels for most applications?

Ans – Because most carbon compounds release a large amount of heat and light on burning.