Chapter 4 · Carbon and its Compounds

NCERT Class 10 Science Chapter 4 Intext Questions (Page 74)

All 2 questions of NCERT Class 10 Science Chapter 4 Intext Questions (Page 74) — Carbon and its Compounds — in the book's order, each with its answer and a step-by-step solution.

1. Q1
   How ​would you ​distinguish experimentally between ​an ​alcohol ​and a carboxylic ​acid?
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   Add sodium hydrogencarbonate: the carboxylic acid fizzes, giving carbon dioxide that turns lime water milky, but the alcohol does not.

   Add a small amount of sodium hydrogencarbonate (or sodium carbonate) to a little of each liquid. The carboxylic acid reacts with brisk effervescence, giving off carbon dioxide that turns lime water milky — ${\text{CH}}_3\text{COOH}+{\text{NaHCO}}_3\to {\text{CH}}_3\text{COONa}+{\text{H}}_2\text{O}+{\text{CO}}_2$ — whereas the alcohol gives no reaction and no gas. As a second test, a carboxylic acid turns blue litmus red while an alcohol has no effect on litmus. (Reaction with sodium metal cannot be used, because both an alcohol and a carboxylic acid give hydrogen with sodium.)

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2. Q2
   What are oxidising agents?
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   Oxidising agents are substances that add oxygen to, or remove hydrogen from, other substances, and are themselves reduced.

   Oxidising agents are substances that are capable of adding oxygen to other substances (or of removing hydrogen from them), that is, substances that oxidise other substances and are themselves reduced in the process. Examples: alkaline potassium permanganate (${\text{KMnO}}_4$) and acidified potassium dichromate (${\text{K}}_2{\text{Cr}}_2{\text{O}}_7$), which add oxygen to ethanol and oxidise it to ethanoic acid — ${\text{CH}}_3{\text{CH}}_2\text{OH}\stackrel{\text{alkaline }{\text{KMnO}}_4+\text{heat}}{\to }{\text{CH}}_3\text{COOH}$. Oxygen itself is also an oxidising agent, as in combustion.

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