Q13
1 markMCQSection A

Assertion (A): Esterification is a process in which a sweet smelling substance is produced.

Reason (R): When esters react with sodium hydroxide an alcohol and sodium salt of carboxylic acid are obtained.


Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below:

Carbon and its Compounds
Properties of Ethanoic Acid

Options

(0)Both A and R are true and R is correct explanation of the Assertion.
(1)Both A and R are true but R is not the correct explanation of the Assertion.
(2)A is true but R is false.
(3)A is false but R is true.
Official Answer

The correct option is (b): Both A and R are true but R is not the correct explanation of the Assertion.

Esterificationsweet-smellingSaponificationsodium hydroxidenot the correct explanation

Marking Scheme

  • 1Evaluation of Assertion (A) as True: 0.5 Mark
  • 2Evaluation of Reason (R) as True and determining it is not the correct explanation: 0.5 Mark

Hint

Recall the definition of esterification and saponification. Are both reactions true? Does the alkaline hydrolysis of an ester explain why esters smell sweet?

Quick Oral Answer

Assertion is true because esterification produces sweet-smelling esters. Reason is also true because esters react with NaOH to give alcohol and sodium carboxylate (saponification). However, the reason does not explain the assertion, so option (b) is correct.

Analysis & Explanation

Let us analyze both statements:

  • Assertion (A): Esterification is indeed a process in which a sweet-smelling substance (an ester) is produced by the reaction of a carboxylic acid with an alcohol in the presence of an acid catalyst. This statement is True.
  • Reason (R): When esters react with an alkali like sodium hydroxide, they are converted back into alcohol and the sodium salt of the carboxylic acid. This reaction is known as saponification (soap preparation). This statement is also True.
  • Relationship: While both statements are scientifically correct, the Reason describes the saponification (hydrolysis) of esters, which is the reverse of esterification. It does not explain why esterification produces a sweet-smelling substance (which is due to the chemical nature of the ester functional group formed). Therefore, R is not the correct explanation of A.

Common Mistakes

  1. 1Students often mark option (a) assuming that since both reactions involve esters, one must explain the other.
  2. 2Confusing esterification (acid + alcohol -> ester) with saponification (ester + base -> alcohol + salt).

Interesting Facts

Esters are widely used in the perfume and food industries to mimic natural flavors and scents, such as banana (amyl acetate), orange (octyl acetate), and pineapple (ethyl butyrate).

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Frequently Asked Questions

How many marks does this question carry in CBSE Class 10 Science 2020?

This question carries 1 mark in the CBSE Class 10 Science 2020 examination.

Which chapter does this question come from in Science?

This question is from the chapter "Carbon and its Compounds" in the CBSE Class 10 Science syllabus.

What topic does this question cover in Science?

This question covers the topic "Properties of Ethanoic Acid" from CBSE Class 10 Science.

What type of question is this in the CBSE Class 10 Science 2020 paper?

This is a MCQ question from Section A in the CBSE Class 10 Science 2020 paper.