CBSE 2025 · Region 2 · Set 1 · Q33 · 5 marks

(A)

An organic compound 'A', molecular formula $\displaystyle \mathrm{C}_{2} \mathrm{H}_{6} \mathrm{O}$ oxidises with $\displaystyle \mathrm{CrO}_{3}$ to form a compound 'B'. Compound 'B' on warming with iodine and aqueous solution of NaOH gives a yellow precipitate of compound 'C'. When compound 'A' is heated with conc. $\displaystyle \mathrm{H}_{2} \mathrm{SO}_{4}$ at $\displaystyle 413$ K gives a compound 'D', which on reaction with excess HI gives compound 'E'. Identify compounds 'A', 'B', 'C', 'D' and 'E' and write chemical equations involved.

(A)

OR 33. (B) (a) Write chemical equations of the following reactions : $\displaystyle \mathbf{3}+\mathbf{1}+\mathbf{1}=\mathbf{5}$

(i)

Phenol is treated with conc. $\displaystyle \mathrm{HNO}_{3}$

(ii)

Propene is treated with $\displaystyle \mathrm{B}_{2} \mathrm{H}_{6}$ followed by oxidation by $\displaystyle \mathrm{H}_{2} \mathrm{O}_{2} / \mathrm{OH}^{-}$.

(iii)

Sodium t-butoxide is treated with $\displaystyle \mathrm{CH}_{3} \mathrm{Cl}$.

(b)

Give a simple chemical test to distinguish between butan-$\displaystyle 1$-ol and butan-$\displaystyle 2$-ol.

(c)

Arrange the following in increasing order of acid strength : phenol, ethanol, water

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.