## Monday, February 1, 2010

### Chemistry Topics Tested in IIT JEE 2009 Question Paper I

1. Van Der Waal's Equation for Real Gases

2. Writing compound name of 2-Bromo-5-hydroxybenzonitrile given the pictorial view of the molecule.
(Cyanide group has higher priority than phenol. Hence correct IUPAC name is
2-Bromo-5-hydroxybenzonitrile)

3. Atomic mass of an element having isotopes

Given that the abundances of isotopes 54Fe, 56Fe and 57Fe are 5%, 90% and 5 %, respectively, the atomic mass of Fe is -
(A) 55.85 (B) 55.95
(C) 55.75 (D) 56.05
[Ans. B]

4. Polymers

Among cellulose, poly(vinyl chloride), nylon and natural rubber, the polymer in which the intermolecular
force of attraction is weakest is -
(A) Nylon (B) Poly(vinyl chloride)
(C) Cellulose (D) Natural Rubber
[Ans. D]
Sol. Natural rubber is an example of elastomers, which has weakest intermolecular forces (dispersion forces).

5. Henry's Law

The solubility of a gas is related to its pressure by Henry's law.

The mass of a gas dissolved per unit volume of the solvent at a given temperature is proportional to the pressure of the gas in equilibrium with the solution.

m = Kp

m = mass of the gas dissolved in a unit volume of the solvent.
p = is the pressure of the gas in equilibrium with the solution
K = proportionality constant

Alternative statement

The pressure of a gas over a solution in which the gas is dissolved is proportional to the mole fraction of the gas dissolved in the solution.

p = Kx

p = partial vapour pressure
x = mole fraction of the gas in the solvent
K = Henry's law constant

Problem
The Henry's law constant for the solubility of N2 gas in water at 298 K is 1.0 × 105

atm. The mole fraction of N2 in air is 0.8. The number of moles of N2 from air dissolved in 10 moles of water at 298 K and 5 atm
pressure is -

6. Acidity order of aromatic carboxylic acids and phenol

Benzoic acid (–COOH) is more acidic than phenol. Electron withdrawing group increase acidic nature &
electron donating group decrease acidity.

7. Among the electrolytes Na2SO4, CaCl2, Al2(SO4)3 and NH4Cl, the most effective coagulating agent for
Sb2S3 sol is -

Sb2S3 is negatively charged sols. Because of the formation higher positive charge ions coagulating power
of Al2(SO4)3 is the highest

8. Reactions of Phosphorous

The reaction of P4 with X leads selectively to P4O6. The X is -

(A) Dry O2 (B) A mixture of O2 and N2
(C) Moist O2 (D) O2 in the presence of aqueous NaOH

P4 is converted to P4O6 in the presence of limited supply of oxygen.

9. Reactions of Sodium

The compound(s) formed upon combustion of sodium metal in excess air is(are) -

10. Defects of Solids

The correct statement(s) regarding defects in solids is(are) -

(A) Frenkel defect is usually favoured by a very small difference in the size of cation and anion
(B) Frenkel defect is a dislocation defect
(C) Trapping of an electron in the lattice leads to the formation of F-center
(D) Schottky defects have no effect on the physical properties of solids

11. Geometrical isomerism of organometallic compounds

12. Stereoisomers

The correct statement(s) about the compound H3C(HO)HC–CH=CH–CH(OH)CH3 (X) is (are)
(A) The total number of stereoisomers possible for X is 6
(B) The total number of diastereomers possible for X is 3
(C) If the stereochemistry about the double bond in X is trans, the number of enantiomers possible for X is 4
(D) If the stereochemistry about the double bond in X is cis, the number of enantiomers possible for X is 2

13. Anilines

p-Amino-N, N-dimethylaniline is added to a strongly acidic solution of X. The resulting solution is treated
with a few drops of aqueous solution of Y to yield blue coloration due to the formation of methylene blue.
Treatment of the aqueous solution of Y with the reagent potassium hexacyanoferrate (II) leads to the
formation of an intense blue precipitate. The precipitate dissolves on excess addition of the reagent.
Similarly, treatment of the solution of Y with the solution of potassium hexacyanoferrate (III) leads to a
brown coloration due to the formation of Z.

Questions: Find compound X,Y and Z

14. Carbonyl Compounds

A carbonyl compound P, which gives positive iodoform test, undergoes reaction with MeMgBr followed
by dehydration to give an olefin Q. Ozonolysis fo Q leads to a dicarbonyl compound R, Which undergoes
intramolecular aldol reaction to give predominantly S.

Questions asked on Structure of P,Q,R and S

15. Attaching these properties to elements in matching
(p) Paramagnetic
(q) Undergoes oxidation
(r) Undergoes reduction
(s) Bond order ≥ 2
(t) Mixing of 's' and 'p' orbitals

16. Matching of characteristic reactions with compounds

(p) Reduction with H2/Pd-C
(q) Reduction with SnCl2/HCl
(r) Development of foul smell on treatment with chloroform and
alcoholic KOH
(s) Reduction with disobutylaluminium hydride (DIBAL-H)
(t) Alkaline hydrolysis

Compounds

(A) CH3CH2CH2CN, (B) CH3CH2OCOCH3, (C) CH3 – CH = CH – CH2OH, (D) CH3CH2CH2CH2NH2

For question paper