CBSE 2025, Set 1

Question

An alkene A with molecular formula C$_5$H$_{10}$ on ozonolysis gives a mixture of two compounds B and C. Compound B gives positive Fehling test and also reacts with iodine and NaOH solution. Compound C does not give Fehling solution test but forms iodoform. Identify the compounds A, B and C.

Edvaya · Accepted Answer

The correct answer is Subjective. **Identifying the compounds:** **Compound B:** - Positive Fehling test $ightarrow$ B is an **aldehyde** (R–CHO) - Positive iodoform test (reacts with I$_2$/NaOH) $ightarrow$ B contains a CH$_3$CHO group - Therefore, **B = Ethanal (CH$_3$CHO)** **Compound C:** - Negative Fehling test $ightarrow$ C is **not an aldehyde** (must be a ketone) - Positive iodoform test $ightarrow$ C contains a CH$_3$CO– group $ightarrow$ **methyl ketone** - Molecular formula constraint (C$_5$H$_{10}$ provides C$_2$ + C$_3$ fragments) $ightarrow$ **C = Propanone (CH$_3$COCH$_3$)** **Compound A:** - Ozonolysis of A yields CH$_3$CHO + CH$_3$COCH$_3$ - Reconnecting the two fragments at the former C=C double bond determines A: $$	extbf{A} = (	ext{CH}_3)_2	ext{C=CHCH}_3 \quad 	extbf{(2-Methylbut-2-ene)}$$ This matches the initial molecular formula C$_5$H$_{10}$.

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Chemistry > Organic Chemistry > Aldehydes Ketones And Carboxylic Acids

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