CBSE 2025 · Region 7 · Set 2 · Q33 · 5 marks
(a)An organic compound (X) having molecular formula $\displaystyle \mathrm{C}_{5} \mathrm{H}_{10} \mathrm{O}$ can show various properties depending on its structures. Draw each of the structures if it :(I)shows Cannizzaro reaction.(II)reduces Tollens' reagent and has a chiral carbon.(III)gives positive iodoform test.(ii)Write the reaction involved in the following :(I)Clemmensen reduction(II)Etard reactionAnswer the following questions :(i)Draw structure of the methyl hemiacetal of methanal.(ii)There are two - $\displaystyle \mathrm{NH}_{2}$ groups in semicarbazide. However only one is involved in the formation of semicarbazones. Give reason.(iii)How will you convert ethanol to $\displaystyle 3$-hydroxybutanal ?(iv)Complete the following equation :
(v)Write the final product formed when phthalic acid is treated with $\displaystyle \mathrm{NH}_{3}$ followed by strong heating.
(a)
An organic compound (X) having molecular formula $\displaystyle \mathrm{C}_{5} \mathrm{H}_{10} \mathrm{O}$ can show various properties depending on its structures. Draw each of the structures if it :
(I)
shows Cannizzaro reaction.
(II)
reduces Tollens' reagent and has a chiral carbon.
(III)
gives positive iodoform test.
(ii)
Write the reaction involved in the following :
(I)
Clemmensen reduction
(II)
Etard reaction
Answer the following questions :
(i)
Draw structure of the methyl hemiacetal of methanal.
(ii)
There are two - $\displaystyle \mathrm{NH}_{2}$ groups in semicarbazide. However only one is involved in the formation of semicarbazones. Give reason.
(iii)
How will you convert ethanol to $\displaystyle 3$-hydroxybutanal ?
(iv)
Complete the following equation :
(v)
Write the final product formed when phthalic acid is treated with $\displaystyle \mathrm{NH}_{3}$ followed by strong heating.
Marking-scheme solution
(i)
(I)
(CH3)3C-CHO
(II)
(III)
CH3-CO-CH2CH2CH3
(ii)
(I)
(II)
(b)
i)
ii) Because semicarbazide undergoes resonance involving only one of the two - NH2 groups,
which is attached directly to the carbonyl-carbon atom.
(iii)
(iv)
v)
Aldehydes, Ketones and Carboxylic AcidsChemical Reactions of Aldehydes, Ketones and Carboxylic AcidsApplylong_answerhard
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CBSE Class 12 Chemistry past-paper question from the 2025board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.