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NEET Chemistry Solved Question Paper 2014

Multiple Choice Questions

31.

Which one of the following is 'd-block element?

32.

If the $E_{cell}^{°}$ for a given reaction has a negative value then which of the following gives the correct relationships for the values of $∆$ G° and K_eq?

$∆ G °$ < 0; K_eq > 1
$∆ G °$ <0; K_eq < 1
$∆ G °$ > 0; K_eq < 1
$∆ G °$ > 0; K_eq > 1

33.

Which of the following is an example for heterogeneous catalysis reaction?

2SO₂(g) + O₂ $\overset{NO (g)}{\to}$ 2SO₃(g)
Hydrolysis of aqueous sucrose solution in the presence of a aqueous mineral acid
2H₂O₂ (l) $\overset{Pt (s)}{\to}$ 2H₂O₂(l) + O₂(g)
Hydrolysis of liquid in the presence of aqueous mineral acid

34.
The relative reactivities of acyl compounds towards nucleophilic substitution are in the order of

acyl chloride > acid anhydride > ester > amide

ester > acyl chloride > amide > acid anhydride

acid anhydride > amide > ester > acyl chloride

acyl chloride> ester> acid anhydride > amide

acyl chloride > acid anhydride > ester > amide

Nucleophilic substitution reaction is a class of reaction in which an electron rich nucleophile selectively bonds with or attacks the positive or partially positive charge of an atom or a group of atoms to replace a leaving group. The ease of nucleophilic substitution depends upon the nature of leaving group. When the leaving tendency of a group in a compound is high, then the compound is more reactive towards nucleophilic substitution. The nucleophilic acyl substitution is completed in two steps as shown below

The reactivity of the compound may be explained on the basicity of the leaving group. A weaker base is a better leaving group. The basicity order is as

CI^- > RCOO^- >RO^- >N $H_{2}^{-}$

Hence, the order of the leaving tendency is

Cl^- > RCOO^- > R-O^- > N $H_{2}^{-}$

and therefore, the order of reactivity of acyl compound is as