Chapter-4 Carbon and its Compounds

Question 1

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

Answer:

Question 2

What would be the electron dot structure of a molecule of sulphur which is made up of eight atoms of sulphur?

Answer:

Question 3

How many structural isomers can you draw for pentane?

Answer:

Question 4

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

Answer:

  • Carbon has the property of self linking. The stability of the C-C bond is very stable because the carbon atom is very small.
  • Carbon is tetravalent and can readily unite with atoms such as hydrogen, oxygen, nitrogen etc

Question 5

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

Answer:

Question 6

Draw the structufes of the following compounds:
(a) Ethanoic acid
(b) Bromopentane
(c) Butanone
(d) Hexanal

Answer:

(a) Ethanoic Acid

(b) Bromopentane

(c) Butanone

(d) Hexanal

Question 7

How would you name the following compounds?

Answer:

(a)Bromoethane

(b)Methanal or Formaldehyde

(c)Hexyne

Question 8

Why is the conversion of ethanol into ethanoic acid an oxidation reaction?

Answer:

Ethanoic acid (CH3COOH) has one oxygen atom more but two hydrogen atoms less than ethanol (C3H5OH).

Loss of hydrogen is called oxidation and gain of oxygen is called oxidation.

Question 9

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

Answer:

A mixture of ethyne and oxygen is used for welding because as both are burnt more heat is produced and a very hot blue flame is produced. Whereas when ethyne and air are burnt only soot flame comes out which results in lesser heat.

Question 10

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

Answer:

If we do a reaction with sodium carbonate, carboxylic acid produces carbon dioxide which turns lime water milky and the same done with alcohol produces no such effect.

The reaction is explained with carboxylic acid:

2CH3COOH + Na2CO3 → 2CH3COONa + H2O + CO2

Question 11

What are oxidising agents?

Answer:

Oxidisng agents are those react by there own or with other substance it would remove hydrogen or will add oxygen. Ex halogens, bromine water and nitric acid.

Question 12

Will you be able to check if water is hard by using a detergent?

Answer:

No, it is not possible to check water is hard by using a detergent. A detergent can’t be used to check hardness whereas a soap can be used to distinguish.

Question 13

People use different methods to wash clothes. Usually after adding the soap, they beat the clothes on a stone or beat them with a paddle, scrub with a brush or the mixture is agitated in a washing machine. Why is this agitation necessary to get clean clothes?

Answer:

The use of soap or detergent is done to loosen the friction between the oil drops carrying dirt particles. All the methods mentioned above loosen the bonds between the cloth and oil particles. Thus the agitation is a more preferd way to clean.

Question 14

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

Question 15

Butanone is a four carbon compound with the functional group
(a) carboxylic acid
(b) aldehyde
(c) ketone
(d) alcohol

Answer:

(c)ketone

Question 16

While cooking, if the bottom of the vessel is 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, that is the reason the blackening happens.

Question 17

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

Answer:

Question 18

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

Answer:

Question 19

What is a homologous series? Explain with an example.

Answer:

Question 20

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

Answer:

Question 21

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:

Question 22

Why are carbon and its compounds used as fuels in most cases?

Answer:

Question 23

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

Answer:

Question 24

What change will you observe by testing soap with litmus paper (blue or red)?

Answer:

Because soap is a base it turn red litmus paper into blue.

Question 25

What is hydrogenation? What is its industrial application?

Answer:

Question 26

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

Answer:

Unsaturated hydrocarbons are known to undergo addition reactions. Among the hydrocarbons mentioned above C3H6 and C2H2 are unsaturated hydrocarbons which undergo addition reactions.

Question 27

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

Answer:

Question 28

Explain the mechanism of the cleaning action of soaps.

Answer:

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