Science (English Medium) कक्षा १२ - CBSE Question Bank Solutions

Arrange the following compounds in decreasing order of acidity.

\[\ce{H2O, ROH, HC ≡ CH}\]

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?

Complete the following reaction.

Three cyclic structures of monosaccharides are given below which of these are anomers.

(I)
(II)
(III)

Structure of a disaccharide formed by glucose and fructose is given below. Identify anomeric carbon atoms in monosaccharide units.

Which of the following monosaccharides are present as five membered cyclic structure (furanose structure)?

(i) Ribose

(ii) Glucose

(iii) Fructose

(iv) Galactose

Name the sugar present in milk. How many monosaccharide units are present in it? What are such oligosaccharides called?

Name the linkage connecting monosaccharide units in polysaccharides.