Archive for the ‘Chemistry’ Category

Chemistry-1996-Set I

Q1) Write the state of hybridisation of Boron in BCI3. (Marks 1)
Ans1)In BCl3 , Boron is sp2 hybridized.

Q2) What are the coordination numbers of each of the ions present in the cubic close packed structure of CaF2 at ordinary temperature and pressure? (Marks 1)
Ans2) Coordination Number for Ca2+ is 8 and for F- is 4.

Q3) The rate constant of a reaction is 2 x 10-2 L mol-1 s-1. What is the order of the reaction?
(Marks 1)

Ans3) Order of the reaction is two.

Q4) Give the IUPAC name of the following compound:


CH3 CH3 (Marks 1)
Ans4) The name of the compound is



Q5) Which alkali metal carbonate decomposes on heating to liberate CO2? (Marks 1)
Ans5) Li2CO3

Q6) Name the first element of the 3-d transition metal series.
(Marks 1)

Ans6) Scandium.

Q7) Give the IUPAC name of the linkage isomer of [ (NH3)3 Pt-NO2 ]Cl. (Marks 1)
Ans7) The linkage isomer of [ (NH3)3 Pt-NO2 ]Cl will be [(NH3)3 Pt (ONO)]Cl. It’s IUPAC name is triamminenitritoplatinum(11) chloride.

Chemistry-1997-Set I

Q 1 State the physical significance of 2.
Ans. 1 2 is the measure of probability of finding an electron in the region around the nucleus.

Q.2 Write which one out of O+2 and O–2 is more stable?
Ans. 2 O+2 is more stable as compared to O-2 because bond order of O+2 is 2.5 while that of O-2 is 1.5.

Q 3 Write an expression in the form of a chemical equation for standard enthalpy of formation of for CO?
Ans. 3 C + 1/2 O2(g) —-> CO(g)

Q 4 Write an expression to relate molar conductivity of an electrotype to its degree of dissociation?

Q 5 What is the ‘ambident group’ ? Give an example.
Ans. 5 Ambident group is one which has more than one attacking site for example -C[-]N- is an ambident nuclleophile.

Q 6 Indicate a chemical reaction involving a homogeneous catalyst ?
Ans. 6 SO2(g) + 1/2 O2(g) —————–> SO3(g)

Q 7 Mention two main function of carbohydrates in plants ?
Ans. 7 Two main function of carbohydrates are :
(1) Cellulose is the chief structural material of plants.
(2) Carbohydrates act as energy storing devices of plants.

Chemistry-1997-Set II

Q 1 What values are permitted for the magnatic quantum number, m for for an electron with angular momentum number, l=2 ?
Ans. 1 When l=2 m=-2 , -1 , 0 , +1 , +2.

Q 3 Name the metal ion with tripositive charge represented by the configuration 1s(2) 2s(2) 2p(6) 3s(2) 3p(6) 3d(6).
Ans. 2 Chromium (Cr)

Q 4 How is the unit of molar conductivity arrived at ?
Ans. Molar conductivity (m) = K x 1000 / Cm (m) = ohm-1cm-1 / moles/cm3

Q 5 Which one among the following is strongest oxidising agent : ClO4-, BrO4-, IO4-.
Ans. BrO4-

Q 11 Calculate the kinetic energy of moving electron which have wavelength of 4.8 pm. (Mass of electron = 9.11 x 10-31 kg, h = 6.63 x 10-34Js)
Ans. 5 = 4.8 pm = 4.8 x 10-12 m
= h / mv
v = 6.6 x 10-34 Js / 9.1 x 10-31 Kg x 4.8 x 10-12m
= 6.6 x 109 / 9.1 x 4.8
= 0.151 x 109 m/s
= 1.151 x 108 m/s
K.E. = 1/2 mv2
= 1/2 x 9.1 x 10-31 x (1.51 x 108)2
= 1/2 x 20.74 x 1015
= 10.37 x 1015 J

Chemistry-1997-Set III

Q 2 Which one out of O+2 and O-2 is more stable.
Ans. 1 O+2 is more stable because its bond order is higher than O-2.

Q 5 How is the unit of molar conductivity arrived at?
Ans. 2 Molar conductivity (m) = K x 1000 / cm
(m) = ohm-1 cm-1 / moles/cm3

Q 6 Which one among the following is strongest oxidising agent : ClO4-, BrO4-, IO4-
Ans. 3 BrO4-

Q 12 The solubility of Ba(OH)2.8H2O in water at 288k is 5.6 g per 100 g of water. What is the molality of the hydroxide ions in the saturated solution of barium hydroxide at 288k? (Atomic mass : Ba=137, O=16, h=1)
Ans. 4 WB = 5.6 g , WB = 100 gm = WB. 100 / MB.WB
= 5.6 x 1000 / 315 x 100 = 0.17
Molarity of Ba(OH) 2.8 H2O = 0.17
Since, one mole Ba(OH) 2.8 H2O will finish two moles of OH- ions.
Molarity of OH- ion = 2 x 0.17 = 0.34 m

Q 16 Consider the following data for the reaction : A + B —–> Products.
Run Initial Conc Initial Conc Initial rate(mols-1)
1 0.10M 1.0M 2.1×10-3
2 0.20M 1.0M 8.4×10-3
3 0.20M 2.0M 8.4×10-3

Determine the order of reaction with respect to A and with respect to B, and the over all order of the reaction.
Ans. Divide Expt. No. (i) and (ii) K [A] [B] = rate of reaction
K[0.20] [1.0] /K[0.10] [1.0] = 8.4 x 10-3/2.1 x 10-3
2 =4 or 2=22 or = 2
So order w.r.t A=2
From Expt.No.(ii) and (iii) it is clear that rate of reaction does not change
in concentration of B, So order W.r.t. B is 1, i.e Rate = k[A]2 [B]o
over all order of reaction = 2

Chemistry-1998-Set I

Q1) Write the MO electronic configuration of a diatomic molecule having a bond order of three? (Marks 1)
Ans.1) 1s2 *1s2 2s2 *2s2 2px2= 2py2 2pz2 (for example – N2)

Q2) What are non-stoichiometric compounds? (Marks 1)
Ans.2) Non-stoichiometric compounds are in which the ratio of the cation’s to the anions is different from that indicated by the chemical formula.

Q3) Complete the nuclear reaction expression? (Marks 1)
Ans.3) 27Co59 (d, p) 27Co60

Q4) Write the IUPAC name of : (Marks 1)

Ans4) 2 – Phenyl propanol.

Q5) Why do noble gases form compounds with fluorine and oxygen only? (Marks 1)
Ans5) Noble gases have very stable configuration and therefore only the most electronegative elements like fluorine and oxygen are able to oxidise them.

Q6) Why is hydrochloric acid not used to acidify a permanganate solution in volumetric estimations of Fe2+ or C2O42- ? (Marks 1)
Ans6) HCl is not used to acidify a permanganate solution is volumetric estimations of Fe2+ or C2O42- because HCl gets oxidised to Cl2 and some quantity of permanganate is used for this.

Chemistry-1998-Set II

Q3) Write the IUPAC name of [Ni(CN)4]2- ion. (Marks 1)
Ans3) IUPAC name of [Ni(CN)4]2- ion is tetracyanonickelate (II) ion.

Q4) Write the IUPAC name of : (Marks 1)



Ans4) IUPAC name of

CH3CCHCH3 is 3-Methyl-2-butanone.


Q6) Complete the nuclear reaction expression : (Marks 1)

Ans6) 13Al27 (,n)15P30

Q9) Why do azo dyes not impart fast colour to fabrics? (Marks 1)
Ans9) Azo dyes do not impart fast colour to fabrics because their interaction with the fabric is one of surface adsorption.

Chemistry-1999-Set I

Q 1 Define an atomic orbital. What does angular momentum quantum number tell about an orbital ?
Ans. 1 Orbital is three dimensional region in space around the nucleus where probability of finding electron is maximum. Angular memento determine the shape of the orbital.

Q 2 Which one of the two, O-2 or O-22 has higher bond order and why?
Ans. 2 O-2 has higher bond order.
O-2 = s 2s2 s*2s2 s2p2z 2p2x 2p2y 2p2x *2p1y
B.O. = 1/2 (8-5) = 1.5
B.O. of O -22 = 1/2 (8-6) = 1

Q 3 Define dislocation in crystal.
Ans. 3 Lattice imperfection extending along a line is known as line defect or dissociation.

Q 4 Write an example of neutral molecule which is isoelectronic to CIO-.
Ans. 4 CIF of HOCl or OF2

Q 5 Express the relationship between degree of dissociation of an electrolyte and its molar.
Ans. 5 = m / m

Q 6 What for are quaternary ammonium salts widely used?
Ans. 6 For detergent.

Q 7 What is meant by Faraday constant?
Ans. 7 It is the charge carried by one mole of electrons or quantity of charge required to deposit one gram equivalent of any element.

Chemistry-1999-Set II

Q 1 Write the number of unpaired electron(s) in an atom of an element with the atomic number 21.
Ans. 1 1

Q 3 How many atoms are there in a unit cell of a metal crystallising in fcc structure?
Ans. 2 4

Q 9 In the formula Fe(h5 – (C5H5)2 what does the prefix ‘h5′ denote.
Ans. h5 – indicate that there are 5 carbon atoms bound to the metal in the compound.

Q 21 For the first row of transition metals the Eo values are :
V Cr Mn Fe Co Ni Cu
Eo(M2+/M) -1.18 -0.91 -1.18 -0.44 -0.28 -0.25 +0.34V

Give suitable explanation for the irregular trend in these values.

Ans. Due to irregular trend in their I.E. values/heat of sublimation/heat as hydration.

Chemistry-1999-Set III

Q 2 In the rock salt structure how many Na+ ions occupy second-nearest neighbour location of a Na+ ion?
Ans. 1 12

Q 3 Which type of hybridisation explains the trigonal bipyramidal shape of SF4 ?
Ans. 2 sp3d

Q 11 Calculate the uncertainity in te velocity of a wagon of mass 3000 kg whose position is known to an accuracy of 10pm. (h = 6.63 x 10-34.Js)
Ans. 3 > h/ 4
v = h / 4pmv = 6.6 x 1034 / 4 x 3.14 x 3000 x 10 x 10-12.
= 1.75 x 10 -27 ms-1

Q 12(i) What is the basic building unit of all silicates?
(ii) How many oxygen atom of this unit are shared with others in the silicate ion Si3O96- ion?

Ans. 4 (i) SiO4
(ii) 2

Q 23 Draw the structure and write the hybridisation state of the central atom of each of the following species :
(i) [Co(NH3)6]3+
(ii) [NiCl4)]2-)

Ans. 5 (i) d2sp3 structural – octahedral
(ii) sp3 structural – tetrahedarl

Chemistry-2000 Set I

Q.1 What is the physical significance of the lines in the following depiction of atomic orbitals?
Ans1. Lines encloses the regions in the space around the nucleus where there is maximum probability of finding the electron.

Q.2 An ionic compound AB2 possesses CaF2 type crystal structure.
Write the co-ordination numbers of A2+ and B- ions in the crystals of AB2.
Ans2. A2+ = 8 B+ = 4

Q.3 How many state of a thermodynamic system be defined?
Ans3. The state of thermodynamic system can be defined in the term of a state of state variable’s that are – pressure, temperature, volume.

Q.4 State Kohlrausch’s low for electric conductance of an electrolyte at infinite dilution.
Ans4. “At infinite dilution, each ion moves independently and contributes to the total molar conductance of an electrolyte.

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