JEE 2013 :: Advanced 2013 :: Chemistry 2013

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

EDTA^4-   is an ethylenediaminetetraacetate ion. The total number of N-Co-O  bond angles in [Co(EDTA)]^- complexion is 

Answer:

Explanation:

Plan EDTA  is a multidentate ligand as it can donate six pairs of electrons -two pair from the two nitrogen atoms and four pair  from the dour  terminal oxygens of the -COO^-  groups 

The structure of a chelate of a divalent Co²⁺ with EDTA is shown as

 Each M has four N-Co-O bonds thus total of eight N-Co-O bonds

 The atomic masses of He and Ne are 4 and 20 amu, respectively. The value of the de-Broglie wavelength of He gas at -73° C is "M"  times that of the de-Broglie wavelength of Ne at 727° C. M is 

Answer:

Explanation:

PLAN     $KE=\frac{1}{2}mv^{2}=\frac{3}{2}RT$

  $\therefore$      $m^{2}v^{2}=2mKE$

     $\therefore$       mv=  $\sqrt{2mKE}$

  $\lambda$   (wavelength)=

$\frac{h}{mv}=-\frac{h}{\sqrt{2mKE}}=\frac{h}{\sqrt{2m(T)}}$

$\lambda$(He  at -73° C=200K)=  $\frac{h}{\sqrt{2\times 4\times200}}$

 $\lambda$ (Ne at 727° C=1000k)

  =    $\frac{h}{\sqrt{2\times 20\times1000}}$

 $\therefore$     $\frac{\lambda_{(He)}}{\lambda_{(Ne)}}=\sqrt{\frac{2\times20\times1000}{2\times4\times200}}=5$

   Thus, M=5

The total number of carboxylic acid groups in the product P is 

Answer:

Explanation:

Plan  Reactant is cyclic  anhydride and changes to dicarboxylic acid on hydrolysis

Also, there is decarboxylation on heating if there is keto group w.r.t -COOH  group. Ozonolysis cleaves $(C=C) $bond and $H_{2}O_{2}$   oxidises -CHO to -COOH group

Thus, number of -COOH group in P=2

  The total number of lone-pairs of electrons in melamine is

Answer:

Explanation:

Plan     Melamine is a heterocyclic  compound

Each nitrogen atom has  one pair of lone pair

Thus, in all six lone pairs

Among P, Q, R, S, the aromatic compound (s) is/are 

Answer:

Explanation:

 Plan A specially said to have aromatic character if 

(a) ring is planar

(b)  there is complete delocalisation of $\pi$  electrons

 (c)    Huckel rule i.e, (4n+2)  rule is followed

 where n is the number of rings (4n+2)=$\pi$ electron delocalised.

                  n      (4n+2)         $\pi$ electrons

P     -       0         2                   2

Q     -       1         6                   6( Including  lone pair)

R     -         1        6                  6( including lone pair on N)

S     -        1         6                   6

In all cases there is complete delocalisation of $\pi$ -electrons 

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