Question 1

Question 1Ethane, with the molecular formula C2H6, has6 covalent bonds7 covalent bonds8 covalent bonds9 covalent bonds

Accepted Answer

7 covalent bondsReason — Ethane, with the molecular formula C2H6, has 7 covalent bonds.

Question 2

Question 2Butanone is a four-carbon compound with the functional groupcarboxylic acidaldehydeketonealcohol

Accepted Answer

ketoneReason — Butanone [C4H8O] has the functional group ketone.

Question 3

Question 3While cooking, if the bottom of the vessel is getting blackened on the outside, it means thatthe food is not cooked completelythe fuel is not burning completelythe fuel is wetthe fuel is burning completely

Accepted Answer

the fuel is not burning completelyReason — While cooking, if the bottom of the vessel is getting blackened on the outside it means that the fuel is not burning completely because certain substances burn partially due to limited supply of oxygen, producing carbon monoxide and soot. The black mark on the vessel is due to the deposition of soot.

Question 4

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

Accepted Answer

Carbon [2, 4] in CH3Cl completes its octet configuration by sharing its 3 electrons with 3 hydrogen [1] atoms and one electron with chlorine [2, 8, 7]. Each of the participating elements attain a stable electronic configuration. Hence, the bonding in CH3Cl is a covalent bonding.Covalently bonded CH3Cl has strong bonds within the molecule but intermolecular forces are weak. Due to this, CH3Cl has low melting and boiling points. As the electrons are shared between atoms, CH3Cl lacks ions, hence, it is a poor conductor of electricity.

Question 5

Question 5Draw the electron dot structures for(a) ethanoic acid(b) H2S(c) propanone(d) F2

Accepted Answer

(a) Ethanoic acid [CH3-COOH](b) H2S(c) Propanone [CH3-CO-CH3](d) F2

Question 6

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

Accepted Answer

A homologous series is a group of organic compounds having a similar structure and similar chemical properties in which the successive compounds differ by a CH2 group.For example,Ethene [C3H6], Butene [C4H8], Propene [C5H10] etc., are part of the alkene homologous series.They differ by a -CH2- unit.The general formula of this series is CnH2n where n = 2, 3, 4 etc.

Question 7

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

Accepted Answer

EthanolEthanoic acidPhysical propertiesColourless liquid with characteristic pleasant odourColourless liquid with pungent odour of vinegarHas a burning tasteHas a sour tasteBoils at 78°CBoils at 118°CFreezes at -117°CFreezes at 16°CChemical propertiesNeutral in nature, hence, does not change the colour of litmus.Acidic in nature, hence, turns wet blue litmus red.Ethanol does not react with metal carbonates / metal hydrogen carbonatesEthanoic acid reacts with metal carbonates / metal hydrogen carbonates to produce salt, carbon dioxide and water.2CH3COOH + Na2CO3 ⟶ 2CH3COONa + H2O + CO2CH3COOH + NaHCO3 ⟶ CH3COONa + H2O + CO2Ethanol does not react with Sodium hydroxide (NaOH)Ethanoic acid reacts with Sodium hydroxide (NaOH) to form Sodium ethanoate.CH3COOH + NaOH ⟶ CH3COONa + H2O

Question 8

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

Accepted Answer

Soaps are molecules in which the two ends have differing properties, one is hydrophilic (water attracting), that is, it interacts with water, while the other end is hydrophobic (water repelling), that is, it interacts with hydrocarbons. Inside water, the soap molecules arrange themselves in a cluster in such a way that the hydrophobic tails are in the interior of the cluster and the hydrophilic (ionic) ends are on the surface of the cluster. This formation is called a micelle.No, micelle formation does not take place in ethanol because the hydrocarbon chains (hydrophobic) of soap becomes soluble in ethanol.

Question 9

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

Accepted Answer

Carbon and its compounds are used as fuels because of the following reasons:They have high calorific value and give out a large amount of heat on combustion due to high percentage of carbon and hydrogen.They are easily combustible due to their optimum ignition temperature.Their combustion can be controlled.

Question 10

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

Accepted Answer

Hardness of water is due to the presence of calcium and magnesium salts. When soap molecules react with these salts, they form a precipitate which appears as a floating off-white layer over water and is called as scum.

Question 11

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

Accepted Answer

Soap is alkaline/basic in nature. Hence, it will turn red litmus blue but no colour change will be observed with blue litmus paper.

Question 12

Question 12What is hydrogenation? What is its industrial application?

Accepted Answer

The addition of hydrogen to unsaturated hydrocarbons in the presence of catalyst such as nickel or palladium to obtain saturated hydrocarbons is called hydrogenation.One of its industrial applications is preparation of vanaspati ghee by catalytic hydrogenation of vegetable oils.

Question 13

Question 13Which of the following hydrocarbons undergo addition reactions:C2H6, C3H8, C3H6, C2H2 and CH4?

Accepted Answer

C3H6, C2H2 will undergo addition reaction as they are unsaturated hydrocarbons.

Question 14

Question 14Give a test that can be used to differentiate between saturated and unsaturated hydrocarbons.

Accepted Answer

When bromine is passed through saturated and unsaturated hydrocarbons, incase of unsaturated hydrocarbon, brown colour of bromine is discharged whereas in case of saturated hydrocarbon brown colour remains brown.

Question 15

Question 15Explain the mechanism of the cleaning action of soaps.

Accepted Answer

Most dirt is oily in nature and oil does not dissolve in water. The molecules of soap are sodium or potassium salts of long-chain carboxylic acids. The ionic-end of soap interacts with water while the carbon chain interacts with oil. The soap molecules, thus form structures called micelles where one end of the molecule is towards the oil droplet while the ionic end faces outside. This forms an emulsion in water. The soap micelle thus helps in pulling out the dirt in water and we can wash our clothes clean.

Question 16

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

Accepted Answer

Electron dot structure of carbon dioxide (CO2) is shown below:

Question 17

Question 2What 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).

Accepted Answer

Electron dot structure of a molecule of Sulphur with eight atoms is shown below:

Question 18

Question 1How many structural isomers can you draw for pentane?

Accepted Answer

Three structural isomers of pentane can be drawn.Pentane [n-pentane]2-Methyl butane [iso-pentane]2,2 Dimethyl Propane [neo-pentane]

Question 19

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

Accepted Answer

Two properties of carbon which lead to the huge number of carbon we see around us are :(a) Catenation — Carbon atoms possess a unique property to link together (self linking) to form very long chains. This property is known as catenation. Catenation is shown by other elements also but Carbon exhibits this property to the maximum extent. This is because carbon-carbon bond is very strong and hence stable.(b) Tetravalency of carbon atoms — Compounds of carbon are formed with oxygen, hydrogen, nitrogen, sulphur, chlorine and many other elements giving rise to compounds with specific properties. The bonds that carbon forms with most other elements are very strong due to its small size hence making these compounds exceptionally stable.

Question 20

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

Accepted Answer

Formula of cyclopentane — C5H10Electron dot structure of cyclopentane

Carbon and its Compounds

Exercises

Intext Questions 1

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Intext Questions 3

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Intext Questions 5