Class 10 Science | Intext Questions & Answers | Chapter 4 | Carbon and its Compounds

Page: 61

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


2. What would be electron dot structure of sulphur which is made up of eight atoms of sulphur.


Page: 68 – 69

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


Three. They are n-pentane, iso-pentane and neo-pentane.

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


(i) Tetravalency                      (ii) Catenation.

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


Molecular formula: C5 H10.

Electron dot structure:

4. Draw the structures for the following compounds:
(i) Ethanoic acid                      (ii) Bromopentane
(iii) Butanone                           (iv) Hexanal


(i) Ethanoic acid (CH3COOH)

(ii) Bromopentane (C5H11Br)

(iii) Butanone (CH3 — CH2 — COCH3)

(iv) Hexanal (C5H11CHO)

5. How would you name the following compounds?


(i) Bromoethane
(ii) Methanal
(iii) 1 – Hexyne

Page: 71

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


Addition of oxygen to a substance is called oxidation. Here, oxygen is added to ethanol by oxidising agent (alkaline potassium permanganate or acidified potassium dichromate) and it is converted into acid.

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


Burning of ethyne in air produces a sooty flame due to incomplete combustion. It is not enough to melt metals for welding.

Page: 74

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




Carboxylic acid

Litmus test

No change in colour.

Blue litmus solution turns red.

Sodium hydrogen carbonate test

C2H5OH + NaHCO3  No reaction


Brisk effervescence due to evolution of CO2.

2. What are oxidising agents?


Oxidising agents are the substances which give oxygen to another substance or remove hydrogen from a substance. E.g., acidic K2Cr2O7. It oxidises ethanol into ethanoic acid.

Page: 76

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


No, because detergents can lather well even in hard water. They do not form insoluble calcium or magnesium salts (scum).

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?


When the cloth wetted in soap solution is agitated or beaten, the micelles containing oily or greasy dirt get removed from the surface of cloth and go into water.

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