NCERT Class X Science Class: Chapter –4. Carbon and its Compounds – Part-9

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Question 33:

A compound X is formed by the reaction of a carboxylic acid and an alcohol in presence of a few drops of . The alcohol on oxidation with alkaline followed by acidification gives the same carboxylic acid as used in this reaction. Give the names and structures of

  1. Carboxylic acid,

  2. Alcohol and

  3. The compound X. Also write the reaction.


(a) Carboxylic acid is ethanoic acid

(b) Alcohol is ethanol

(c) X is ethyl ethanoate

Question 34:

Why detergents are better cleansing agents than soaps? Explain.


Detergents are the better cleansing agents than soaps because detergents work as cleansing agent both in hard and soft water.

Soaps are not suitable for use with hard water .The charged ends of detergents do not form insoluble precipitates with calcium and magnesium ions in hard water. Also detergents produce more than soap

Question 35:

Name the functional groups present in the following compounds


(a) Ketone:

Image the structure of ketone

Image the Structure of Ketone

(b) Carboxylic acid:

ImageCarboxylic acid

ImageCarboxylic Acid

(c) Aldehyde:

Image the Aldehyde

Image the Aldehyde

(d) Alcohol:

Image the alcohol

Image the Alcohol

Question 36:

How is ethane prepared from ethanol? Give the reaction involved in it.


Ethanol on heating with excess concentrated sulphuric acid at results in the dehydration of ethanol to give ethene.

The concentrated sulphuric acid can be regarded as a dehydration agent, which remove water from ethanol.

Image reaction of concentrated sulphuric acid and ethanol

Image Reaction of Concentrated Sulphuric Acid and Ethanol

Question 37:

Intake of small quantity of methanol can be lethal. Comment.


Methanol is oxidized to Methanal in the liver. Methanal reacts rapidly with the components of cells. It causes the protoplasm to coagulate. It also affects the optic nerve, causing blindness.

Question 38:

A gas is evolved when ethanol reacts with sodium. Name the gas evolved and also write the balanced chemical equation of the reaction involved.


When ethanol reacts with sodium, it leaves off hydrogen gas, and sodium Ethoxide is formed in that process. Hence, hydrogen gas is evolved during this process. A balanced chemical equation of the reaction involved:

Use this equation to release hydrogen gas from ethanol and sodium reaction:

Gas evolved is hydrogen,

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