Science (English Medium) Class 12 - CBSE Question Bank Solutions for Chemistry

Write steps to carry out the conversion of phenol to aspirin.

Explain why p-nitrophenol is more acidic than phenol.

Match the structures of the compounds given in Column I with the name of the compounds given in Column II.

	Column I	Column II
(i)		(a) Hydroquinone
(ii)		(b) Phenetole
(iii)		(c) Catechol
(iv)		(d) o-Cresol
(v)		(e) guinone
(vi)		(f) Resorcinol
		(g) Anisole

Match the starting materials given in Column I with the products formed by these (Column II) in the reaction with HI.

	Column I		Column II
(i)	CH3—O—CH3	(a)
(ii)	\[\begin{array}{cc} \ce{CH3}\phantom{..................}\\ \backslash\phantom{.............}\\ \ce{CH-O-CH3}\\ /\phantom{..............}\\ \ce{CH3}\phantom{..................} \end{array}\]	(b)	\[\begin{array}{cc} \ce{CH3}\phantom{....}\\ |\phantom{.......}\\ \ce{CH3-C-I + CH3OH}\\ |\phantom{.......}\\ \ce{CH3}\phantom{....} \end{array}\]
(iii)	\[\begin{array}{cc} \ce{CH3}\phantom{.}\\ |\phantom{....}\\ \ce{H3C-C-O-CH3}\\ |\phantom{....}\\ \ce{CH3}\phantom{..} \end{array}\]	(c)
(iv)		(d)	CH3—OH + CH3—I
		(e)	\[\begin{array}{cc} \ce{CH3}\phantom{.....................}\\ \backslash\phantom{.................}\\ \ce{CH-OH + CH3I}\\ /\phantom{.................}\\ \ce{CH3}\phantom{.....................} \end{array}\]
		(f)	\[\begin{array}{cc} \ce{CH3}\phantom{.....................}\\ \backslash\phantom{.................}\\ \ce{CH-I + CH3OH}\\ /\phantom{.................}\\ \ce{CH3}\phantom{.....................} \end{array}\]
		(g)	\[\begin{array}{cc} \ce{CH3}\phantom{....}\\ |\phantom{.......}\\ \ce{CH3-C-OH + CH3I}\\ |\phantom{.......}\\ \ce{CH3}\phantom{....} \end{array}\]

Assertion: Addition reaction of water to but-1-ene in acidic medium yields butan-1-ol.

Reason: Addition of water in acidic medium proceeds through the formation of primary carbocation.

Assertion: p-nitrophenol is more acidic than phenol.

Reason: Nitro group helps in the stabilisation of the phenoxide ion by dispersal of negative charge due to resonance.

Assertion: IUPAC name of the compound

\[\begin{array}{cc}
\ce{CH3 - CH - O - CH2 - CH2 - CH3}\\  
|\phantom{....................}\\
\ce{CH3}\phantom{.................}
\end{array}\] is 2-Ethoxy-2-methylethane.

Reason: In IUPAC nomenclature, ether is regarded as hydrocarbon derivative in which a hydrogen atom is replaced by —OR or —OAr group [where R = alkyl group and Ar = aryl group]

Assertion: Like bromination of benzene, bromination of phenol is also carried out in the presence of Lewis acid.

Reason: Lewis acid polarises the bromine molecule.

Assertion: Phenol forms 2, 4, 6 – tribromophenol on treatment with \[\ce{Br2}\] in carbon disulphide at 273 K.

Reason: Bromine polarises in carbon disulphide.

Assertion: Phenols give o- and p-nitrophenol on nitration with conc. \[\ce{HNO3}\] and \[\ce{H2SO4}\] mixture.

Reason: –OH group in phenol is o–, p– directing.

Write complete reaction for the bromination of phenol in aqueous and non-aqueous medium.

Explain why Lewis acid is not required in bromination of phenol?

How can phenol be converted to aspirin?

In Clemmensen Reduction carbonyl compound is treated with:

Treatment of compound \[\begin{array}{cc}
\phantom{.....}\ce{O}\\
\phantom{.....}||\\
\ce{Ph - O - C - Ph}
\end{array}\] with \[\ce{NaOH}\] solution yields

(i) Phenol

(ii) Sodium phenoxide

(iii) Sodium benzoate

(iv) Benzophenone

Arrange the following in decreasing order of their acidic strength. Give explanation for the arrangement.

\[\ce{C6H5COOH, FCH2COOH, NO2CH2COOH}\]

Assertion: Compounds containing \[\ce{-CHO}\] group are easily oxidised to corresponding carboxylic acids.

Reason: Carboxylic acids can be reduced to alcohols by treatment with \[\ce{LiAlH4}\].

Write down functional isomers of a carbonyl compound with molecular formula \[\ce{C3H6O}\]. Which isomer will react faster with \[\ce{HCN}\] and why? Explain the mechanism of the reaction also. Will the reaction lead to the completion with the conversion of whole reactant into product at reaction conditions? If a strong acid is added to the reaction mixture what will be the effect on concentration of the product and why?

Complete the following reaction.

The letters ‘D’ or ‘L’ before the name of a stereoisomer of a compound indicate the correlation of configuration of that particular stereoisomer. This refers to their relation with one of the isomers of glyceraldehyde. Predict whether the following compound has ‘D’ or ‘L’ configuration.