NCERT Class X Science Solutions: Chapter 4 – Carbon and its Compounds Part 2

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Question 6:

What is a homologous series? Explain with an example.

Answer:

A homologous series is a series of carbon compounds that have different numbers of carbon atoms but contain the same functional group.

Homologous series

Alkane

No. of Carbons

Structure

Formula

Ethene

2

Propene

3

Butene

4

Pentene

5

For example: methane, ethane, propane, butane, etc. are all part of the alkane homologous series. The general formula of this series is.

  • Methane CH4

  • Ethane CH3CH3

  • Propane CH3CH2CH3

  • Butane CH3CH2CH2CH3

It can be noticed that there is a difference of −CH2 unit between each successive compound. Science

Question 7:

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

Answer:

  • Ethanol is a liquid at room temperature with a pleasant odor while ethanoic acid has vinegar-like smell. The melting point of ethanoic acid is 17°C. This is below room temperature and hence, it freezes during winters.

  • Ethanoic acid reacts with metal carbonates and metal hydrogen carbonates to form salt, water, and carbon dioxide gas while ethanol does not react with them.

  • For example,

  • For example,

Question 8:

In the electrolytic refining of a metal M, what would you take as the anode, the cathode and the electrolyte?

Answer:

In the electrolytic refining of a metal M:

  • Anode Impure metal M

  • Cathode Thin strip of pure metal M

  • Electrolyte Solution of salt of the metal M

Question 9:

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

Answer:

Most of the carbon compounds give a lot of heat and light when burnt in air. Saturated hydrocarbons burn with a clean flame and no smoke is produced. The carbon compounds, used as a fuel, have high calorific values. Therefore, carbon and its compounds are used as fuels for most applications.