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

Assertion: \[\ce{Cr(H2O)6]Cl2 and [Fe(H2O)6]Cl2}\] are reducing in nature.

Reason: Unpaired electrons are present in their d-orbitals.

What is the relationship between observed colour of the complex and the wavelength of light absorbed by the complex?

Which of the following compounds are gem-dihalides?

(i) Ethylidene chloride

(ii) Ethylene dichloride

(iii) Methylene chloride

(iv) Benzyl chloride

IUPAC name of m-cresol is ______.

IUPAC name of the compound \[\begin{array}{cc}
\ce{CH3 - CH - OCH3}\\
\phantom{}|\phantom{....}\\
\phantom{}\ce{CH3}\phantom{..}
\end{array}\] is ______.

Give IUPAC name of the compound given below.

\[\begin{array}{cc}
\phantom{}\ce{CH3 - CH - CH2 - CH2 - CH - CH3}\phantom{.}\\
\phantom{.........}|\phantom{...................}|\phantom{...........}\\
\phantom{..}\ce{Cl}\phantom{.................}\ce{OH}\phantom{..}
\end{array}\]

Which of the following compounds will react with sodium hydroxide solution in water?

Which of the following reagents can be used to oxidise primary alcohols to aldehydes?

(i) \[\ce{CrO3}\] in anhydrous medium.

(ii) \[\ce{KMnO4}\] in acidic medium.

(iii) Pyridinium chlorochromate.

(iv) Heat in the presence of Cu at 573 K.

Write the IUPAC name of the compound given below.

\[\begin{array}{cc}
\phantom{}\ce{CH3 - CH2 - C = C - OH}\\
\phantom{........}|\phantom{....}|\phantom{}\\
\phantom{..............}\ce{CH3 CH2OH}
\end{array}\]

What happens when benzene diazonium chloride is heated with water?

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.