JEE 2013 :: Advanced 2013 :: Chemistry 2013

• Advanced 2013 - Physics 2013
• Advanced 2013 - Chemistry 2013
• Advanced 2013 - Mathematics 2013

After completion of the reactions (i and II), the organic compound (s) in reaction mixtures is (are )

Answer:

Explanation:

Plan  when acetone reacts with Br₂ in Basic medium , bromoform is formed

 Reaction I

 $CH_{3}COOCH_{3}(  1 mol, 1/3 mol )+3Br_{2}( 3 mol, 1 mol  )+4NaOH\rightarrow$

                                                  $ CH_{3}COONa+CHBr_{3}+3NaBr+3H_{2}O$

                                                                 (U)              (T)

 when CH₃COCH₃ are Br₂ are in equimolar quantity , all the Br₂ (limiting reactant)  is converted into desired products and 2/3 mole of CH₃COCH₃ remains unreacted, being in excess

 when acetone  reacts with Br₂ in acidic medium, there is monobromination of acetone

 Reaction II

$CH_{3}COCH_{3}+Br_{2}$   $\underrightarrow{CH_{3}COOH}$ 

                                                                            $CH_{3}COCH_{2}Br+HBr$ 

   1 mol                 1 mol                                         (p)

 CH₃COCH₃ and Br₂ react 1:1 mole ratio and (P) is formed

 in reaction I, (U) and (T) are formed and acetone (reactant) remains  unreacted

 In reaction II, (P) is formed

The major product(s) of the following reaction is (are)

Answer:

Explanation:

Plan - OH group is activating   group and is o- and p- directing

 Also- SO₃H is a better leaving group and is knocked out by Br^-

In the following reaction, the products(s) formula is (are)

Answer:

Explanation:

Plan phenolic compounds in alkaline solution react with chloroform (CHCl₃)  ata  temperature lower than that of CHCl₃ to form  ortho- isomer as the major  product (due to greater stability resulting from intramolecular hydrogen  bonding )

major as stable due to interamolecular H-bonding

 The K_sp of Ag₂CrO₄ is 1.1 x 10^-12 at 298 K. The solubility (in mol/L)  of Ag₂CrO₄ in a 0.1 M AgNO₃ solution is 

Answer:

Explanation:

 Plan in presence of common ion (in this case Ag⁺ ion )  solubility of sparingly soluble salt is decreased

 Let solubility of Ag₂CrO₄ in presence of 0.1 m

 AgNO₃  =x

 $Ag_{2}CrO_{4}\rightleftharpoons 2Ag^{+}+CrO_2^{4-}$

                                       2x                x

$ AgNO_{3}\rightleftharpoons Ag^{+}+NO_3^{-}$

                                    0.1          0.1

Total [Ag⁺]= [2x+0.1]M

 = 0.1 M as x<<< 0.1 M

 $ [Cr_{4}^{2-}]=x M$

 thus, $[Ag^{+}]^{2+}[CrO^{2-}_{4}]= K_{sp}$

 (0.1)² (x)=1.1 x 10^-12

  $\therefore$       x= $1.1\times 10^{-10}$ M

A tetrapeptide has a -COOH  group on alanine. This  produces glycine (Gly), valine (Val), phenylalanine (Phe)  and alanine (Ala)  on complete hydrolysis, For this tetrapeptide, the number of possible sequences (primary structures) with -NH₂  group attached  to a chiral center is 

Answer:

Explanation:

Plan A peptide linkage is hydrolysed to two free amino acids.

C'  is a chiral carbon tetrapeptide that has four amino acids joined by three peptide linkage.

-COOH group is on the alanine part, thus it is a fixed C-terminal position in each combination.

Glycine is optically inactive thus it can't be on the N-terminal side.

 Thus, possible combinations are

Phe-Gly-Val-Ala

Phe-Val-Gly-Ala

Val-Gly-Phe-Ala

Val-Phe-Gly-Ala

Thus, in all four possible combinations``

• Advanced 2013 - Physics 2013
• Advanced 2013 - Chemistry 2013
• Advanced 2013 - Mathematics 2013