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

Which of the following statements are correct about this reaction?

(i) The given reaction follows S_N2 mechanism.

(ii) (b) and (d) have opposite configuration.

(iii) (b) and (d) have same configuration.

(iv) The given reaction follows S_N1 mechanism.

Which of the following statements are correct about the kinetics of this reaction?

(i) The rate of reaction depends on the concentration of only (b).

(ii) The rate of reaction depends on concentration of both (a) and (b).

(iii) Molecularity of reaction is one.

(iv) Molecularity of reaction is two.

Ethylene chloride and ethylidene chloride are isomers. Identify the correct statements.

(i) Both the compounds form same product on treatment with alcoholic KOH.

(ii) Both the compounds form same product on treatment with aq.NaOH.

(iii) Both the compounds form same product on reduction.

(iv) Both the compounds are optically active.

Which of the compounds will react faster in S_N1 reaction with the ^–OH ion?

\[\ce{CH3-CH2-Cl}\] or \[\ce{C6H5-CH2-Cl}\]

Compound ‘A’ with molecular formula \[\ce{C4H9Br}\] is treated with aq. \[\ce{KOH}\] solution. The rate of this reaction depends upon the concentration of the compound ‘A’ only. When another optically active isomer ‘B’ of this compound was treated with aq. \[\ce{KOH}\] solution, the rate of reaction was found to be dependent on concentration of compound and \[\ce{KOH}\] both.

(i) Write down the structural formula of both compounds ‘A’ and ‘B’.

(ii) Out of these two compounds, which one will be converted to the product with inverted configuration.

Write the structures and names of the compounds formed when compound ‘A’ with molecular formula, \[\ce{C7H8}\] is treated with \[\ce{Cl2}\] in the presence of \[\ce{FeCl3}\].

How do polar solvents help in the first step in S_N1 mechanism?

Elimination reactions (especially β-elimination) are as common as the nucleophilic substitution reaction in case of alkyl halides. Specify the reagents used in both cases.

Aryl halides are extremely less reactive towards nucleophilic substitution. Predict and explain the order of reactivity of the following compounds towards nucleophilic substitution:

(I)
(II)
(III)

Cyanide ion acts as an ambident nucleophile. From which end it acts as a stronger nucleophile in aqueous medium? Give reason for your answer.

Match the reactions given in Column I with the types of reactions given in Column II.

	Column I	Column II
(i)		(a) Nucleophilic aromatic substitution
(ii)	\[\begin{array}{cc} \ce{CH3 - CH = CH2 + HBr -> CH3 - CH - CH3}\\ \phantom{............................}|\phantom{}\\ \phantom{.............................}\ce{Br}\phantom{} \end{array}\]	(b) Electrophilic aromatic substitution
(iii)		(c) Saytzeff elimination
(iv)		(d) Electrophilic addition
(v)	\[\begin{array}{cc} \ce{CH3  CH2 CH CH3 ->[alc.KOH] CH3  CH = CH CH3}\\ \phantom{}|\phantom{..........................}\\ \phantom{}\ce{Br}\phantom{........................} \end{array}\]	(e) Nucleophilic substitution (SN1)

Why are aryl halides less reactive towards nucleophilic substitution reactions than alkyl halides?

Mark the correct order of decreasing acid strength of the following compounds.

(a)
(b)
(c)
(d)
(e)

Out of o-nitrophenol and o-cresol which is more acidic?

Assertion: o-Nitrophenol is less soluble in water than the m- and p-isomers.

Reason: m- and p- Nitrophenols exist as associated molecules.

What is the role of pyridine in the acylation reaction of amines?

Assertion: Acylation of amines gives a monosubstituted product whereas alkylation of amines gives polysubstituted product.

Reason: Acyl group sterically hinders the approach of further acyl groups.

Glycogen is a branched-chain polymer of α-D-glucose units in which chain is formed by C1 – C4 glycosidic linkage whereas branching occurs by the formation of C1 – C6 glycosidic linkage. Structure of glycogen is similar to ______.

Which of the following polymer is stored in the liver of animals?

Which of the following polymers can have strong intermolecular forces?

(i) Nylon

(ii) Polystyrene

(iii) Rubber

(iv) Polyesters