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CBSE Class 10 Science Question 43 of 45

Solved 2024 Sample Question Paper CBSE Class 10 Science — Question 1

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Question 37

The table given below shows the hints given by the quiz master in a quiz.

S. No.HINT
(i)Substance 'C' is used as a preservative.
(ii)'C' has two carbon atoms; 'C' is obtained by the reaction of 'A' in presence of alkaline Potassium permanganate followed by acidification.
(iii)Misuse of 'A' in industries is prevented by adding Methanol, Benzene, and pyridine to 'A'.
(iv)'F' is formed on heating 'A' in presence of conc Sulphuric acid.
(v)'F' reacts with Hydrogen gas in presence of Nickel and Palladium catalyst.

Based on the above hints answer the following questions

(a) Give the IUPAC names of A and F

(b) Illustrate with the help of chemical equations the changes taking place. (A ⟶ C and A ⟶ F)

OR

(b) Name the chemical reactions which occur in steps 2 and 5. Identify the compounds formed in these steps if 'A' is replaced with its next homologue.

Answer

(a) From step 3 we can conclude that A is Ethanol

From step 5 we can conclude that F is Ethene

CH3CH2OH A→ Hot conc.H2SO4CH2=CH2+H2O F\underset{\text{ A} }{\text{CH}_3\text{CH}_2\text{OH}} \underset{ \text{H}_2\text{SO}_4}{\xrightarrow{\text{ Hot conc.}}} \underset{\text{ F}}{\text{CH}_2=\text{CH}_2 + {\text{H}_2\text{O}}}

(b) A ⟶ C

CH3CH2OH A→ alkaline KMNO4+Heat+ H+ or acidified K2Cr2O7+HeatCH3COOH C\underset{\text{ A} }{\text{CH}_3\text{CH}_2\text{OH}} \underset{ \text{ or acidified K}_2\text{Cr}_2\text{O}_7 + \text{{Heat}} }{\xrightarrow{\text{ alkaline KMNO}_4+ \text{Heat} + \text{ H}^+}} \underset{\text{ C} }{ \text{CH}_3\text{COOH} }

A ⟶ F

CH3CH2OH A→ Hot conc.H2SO4CH2=CH2+H2O F\underset{\text{ A} }{\text{CH}_3\text{CH}_2\text{OH}} \underset{ \text{H}_2\text{SO}_4}{\xrightarrow{\text{ Hot conc.}}} \underset{\text{ F}}{\text{CH}_2=\text{CH}_2 + {\text{H}_2\text{O}}}

OR

(b) Step 2 is oxidation of ethanol.

CH3CH2OH A→ alkaline KMNO4+Heat+ H+ or acidified K2Cr2O7+HeatCH3COOH C\underset{\text{ A} }{\text{CH}_3\text{CH}_2\text{OH}} \underset{ \text{ or acidified K}_2\text{Cr}_2\text{O}_7 + \text{{Heat}} }{\xrightarrow{\text{ alkaline KMNO}_4+ \text{Heat} + \text{ H}^+}} \underset{\text{ C} }{ \text{CH}_3\text{COOH} }

Step 5 is hydrogenation as ethene reacts with hydrogen gas. It is also called an addition reaction.

CH2 = CH2 + H2 ⟶ CH3 - CH3 [ethane]

When ethanol is replaced by propanol then propene is formed instead of ethene.

C3H7OH Propanol→ Hot conc.H2SO4C3H6+H2O Propene\underset{\text{ Propanol} }{\text{C}_3\text{H}_7\text{OH}} \underset{ \text{H}_2\text{SO}_4}{\xrightarrow{\text{ Hot conc.}}} \underset{\text{ Propene}}{\text{C}_3\text{H}_6 + {\text{H}_2\text{O}}}