JEE 2014 :: Main 2014 :: Chemistry 2014

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 In the reaction,  $CH_{3}COOH$    $\underrightarrow{LiAlH_{4}}$  A   $\underrightarrow{PCl_{5}}$ B   $\underrightarrow{Alc.KOH}$  C .The product C is

Answer:

Explanation:

 This problem is based on successive reduction, chlorination and elimination reaction. To solve such a problem, use the function of the given reagents.

(i) LiAlH₄  causes a reduction

(ii) PCl₅ causes chlorination

(iii)  Alc. KOH causes elimination reaction

    $CH_{3}COOH$ $\underrightarrow{LiAlH_{4}}$ $CH_{3}CH_{2}OH$ (A) $\underrightarrow{PCl_{5}}$

    $CH_{3}CH_{2}Cl$ (B) $\xrightarrow[{Alc.KOH}]{-HCl}$ $CH_{2}=CH_{2}$ (C)

Which one of the following bases is not present in DNA?

Answer:

Explanation:

Quinoline is an alkaloid, it is not present in DNA, DNA has four nitrogen bases in adenine,  guanine, cytosine and thymine.

 Which one is classified as a condensation polymer?

Answer:

Explanation:

  Dacron is a condensation polymer of ethylene glycol and methyl terephthalate. The formation of  dacron can be shown as 

 Here, elimination of MeOH occurs as a by-product. So, this reaction is known as condensation polymerisation.

For which of the following molecule significant   $\mu\neq 0$   ?

Answer:

Explanation:

Draw  the structure of organic  compounds  indicationg net dipole  moment  which includes lone pair  and bond angle also

-OH groups and -SH groups do not cancel  their dipole moment as they exist in different conformation.

 Considering the basic strength of amines in an aqueous solution, which one has the smallest pK_b, value?

Answer:

Explanation:

 This problem can be solved by using the concept of effect of steric hindrance, hydration and  H-bonding in basic strength of amines.

 Order of basic  strength  of aliphatic  amine solution is as follows (order of K_b)

  $ ( CH_{3})_{2}\ddot{N}H>CH_{3}\ddot{N}H_{2}>(CH_{3})_{3}\ddot{N}>C_{6}H_{5}\ddot{N}H_{2}$

  as we know, pK_b  =-log K_b. So, $ ( CH_{3})_{2}\ddot{N}H$  will have smallest pK_b value.

 In case of phenylamine, N is attached to sp² hybridised carbon, hence it has highest pK_b and least basic strength.

• Main 2014 - Physics 2014
• Main 2014 - Chemistry 2014
• Main 2014 - Mathematics 2014