CH-4   Carbon and it’s compound

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.