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IITJEE
Model Paper
Chemistry Mains
Time :120 Mins Max Marks: 100
1. a)Two non reacting gases are taken in a vessel and allowed to effuse out through a pinhole in vacuum. At a particular time it is found that total 1.5 moles of gas have been effused out from an equimolar mixture (1 mole each initially) of two gases. If one gas is NO2 and the molecular weight of the other gas is 1.5 times of the average molecular weight of the mixture of gas effused out, then calculate the average molecular weight of gas mixture left in the vessel. [7]
b)
Write the IUPAC name of the following complex.
[Pt(NH3)(H2O)(C6H5N)(NO2)]NO3 [2]
c) What is the hybridisation and shape
of TeF5? [2]
2.a)
A weak acid HA exists partially as
trimer. If freezing point of a solution of this acid having 0.03 mole fraction
of acid in benzene is 276.9 K, then calculate the equilibrium constant for
trimerisation of HA. Freezing point of benzene is 278.4 K and latent heat of
fusion of benzene is 10.042 K Joule mol-1.(Hint. Assume molality of
the solution as same as molarity.) [7]
b)Cu2+
is ‘d9’ system. But [Cu(NH3)4]2+ is
a dsp2 complex explain.
- A finely powdered mineral of calcium ‘A’ was
boiled with Na2CO3 solution and the precipitate was filtered off. The
filtrate was cooled and after cooling another precipitate ‘B’ produced
which normally exists in the hydrated form. The aqueous solution of ‘B’ is alkaline. When ‘B’
is strongly heated , it gives compound ‘C’ along with glassy bead ‘D’. ‘C’
was also present initially into filtrate. ‘D’ is fused with one of the
metal sulphate ‘E’ to give green colour both in oxidising flame and
reducing flame. Identify A to E with reaction and give the explanation.
[12]
- a) Let MgTiO3 exist in pervoskite
structure. In this lattice, all the atoms of one of the face diagonals are
removed. Calculate the density of unit cell if the radius of Mg2+
is 0.72Å and
the corner ions are touching each other. [ Atomic mass of Mg=24, Ti=48]
[6]
b) A cell is represented as
follows
Zn| Zn2+ ||
HCl |Pt,H2(g) E0Zn2+/Zn
= - 0.76 V
0.1 M 1 atm
If the volume of HCl
solution in the RHS half cell is 1.5 litre then calculate the weight of NaOH
(70% by pure weight) required to be added in the H+ containing half
cell to consume all H+ from that half cell. Given emf of this cell
is 0.701 volt at 250C before its use. What is the change in emf of
the cell after addition of NaOH. [10]
5. a)
Predict the major products in the following reaction with proper mechanism.
I [4]
6. a) Eyes pass a signal to the brain when the visual receptors are
struck by photons of wavelength 850 nm. If a total energy of 3.15*10-15
J is required to trip the signal , what is the minimum number of photons that
must strike the receptor to pass a signal? [6]
b) To determine the concentration
of HCN in blood of a patient a doctor decided to titrate a dilute sample of the
blood with KI solution of I2. A diluted blood sample of 15ml was
titrated with 5.21 ml of an I3- solution . 10.42 ml of
this I3- was needed 1.222gm sample of As4O6 for complete
reaction.
Calculate the molar concentration
of HCN in blood.
Atomic wt of As=75, I=127.
It is also given As4O6
converts into H3AsO3 in solution. [9]
7.a) Convert Benzene to p-methylbenzoic
acid through formation of Grignard reagent. [3]
PhS-
b) Identify A and B in the following reaction
CH2=CH-CMe2Cl A+B [2]
c) A
compound having molecular formula C7H7Cl exists in three isomeric forms, A,B,C
in which C has maximum dipole moment . When they are treated with NaNH2
in liq NH3 they yield three different isomeric product X,Y,Z as
follows:
A in the
presence of NaNH2 in liq NH3 gives all the three products
X,Y,Z
B in the presence of NaNH2 in liq NH3 gives only X and Y
C in the
same condition gives Y and Z
Identify
A,B,C and X,Y,Z with proper explanation. [8]
8. 0.0852
gm of organic halide (A) when dissolved in 2gm of camphor, the melting point of
the mixture was found to be 1670C. Compound (A) when heated with Na
in dry ether gives a gas (B). 280 ml of gas(B) at STP weighs 0.375 gm. Showing
different steps, give structural formula of (A) and (B). [Kf for
camphor=40, m.p of camphor=1790C] [7]
9. An acid
(A) when heated gives another acid (B). (B) when treated with Ca(OH)2
and heated (C) is obtained . Another compound (D) having molecular formula C9H18
gives (C) and (E) due to Ozonolysis. (C) didn’t reduce Fehling’s solution but
(E) did. (E) after catalytic hydrogenation gives (F) which treated with conc H2SO4
to give (G) which again due to Ozonolysis gives (I) and (H). (I) can reduce
Tollen’s reagent but (H) can’t. Identify (A) to (I). [9]
10.
Equilibrium constants of T2O (1T3 is the
isotope of 1H1) differ from those of H2O at
298K. Let at 298K pure T2O has pT(Like pH) =7.62. Find out the pT of
a solution prepared by adding 10ml of 0.2M TCl to 15ml of 0.25M NaOT.
[5]