Exam Details
| Subject | chemistry | |
| Paper | paper 1 | |
| Exam / Course | indian forest service | |
| Department | ||
| Organization | union public service commission | |
| Position | ||
| Exam Date | 2014 | |
| City, State | central government, |
Question Paper
selecting at least ONE question from each of the two Sections A and B.
Allempts of questions shall be counted chronological order. Unless struck off. atle_mpl of a question shall
be counted even if allempted partly. Any page or portion of the page left· blank in the Answer B90k must
he clearly struck off.
All questions carry equal f1U!l'/cs. The number of marks carried by a question/part is indicated against it.
Answers must be written in ENGUSH only.
Unless otherwis.. .mentioned, symbols and notations have their usual. standard meanings.
Assume suitable data, if necessary and indicate' the same clearly.
Neat sketches may be drawn, wherever required
SECTION-A
6.626, x ur34 JS; kg 1.38 x J0-23 J 8.314 J...1 mo1-1; rr 3.14;
RH 10973731.6 c 3 Ja8
· Q. 1. Answer briefly au the parts 10X4=40
selecting at least ONE question from each of the two Sections A and B.
Allempts of questions shall be counted chronological order. Unless struck off. atle_mpl of a question shall
be counted even if allempted partly. Any page or portion of the page left· blank in the Answer B90k must
he clearly struck off.
All questions carry equal f1U!l'/cs. The number of marks carried by a question/part is indicated against it.
Answers must be written in ENGUSH only.
Unless otherwis.. .mentioned, symbols and notations have their usual. standard meanings.
Assume suitable data, if necessary and indicate' the same clearly.
Neat sketches may be drawn, wherever required
SECTION-A
6.626, x ur34 JS; kg 1.38 x J0-23 J 8.314 J...1 mo1-1; rr 3.14;
RH 10973731.6 c 3 Ja8
· Q. 1. Answer briefly au the parts 10X4=40
jc-HENT-N-BGDLA I
CHEMISTRY
Paper-I
Inme Allowed Three Hours I
Maximum Marks 100 j
· QUESTION PAPER SPECIFIC INSTRUCTIONS
Plet1se read each of the following instructions carefully be/ ore aJtempting questions
There are EIGHT questions in all, out of which FIVE are to be attempted.
Question nos. J and S are compulsory. Out of the remaining SIX questions, THREE. are to be attempted
Q. A Phase Rule can be written as F C where F is the number of degrees of freedom, P is the number of phases and C is the number of components.
Define the tenns degree freedom; phase and component. ·
Use the Phase Rule to show why, when plotting a phase diagram of a 2-component system, it is necessary to fix a yariable (usually volume).
6,4
Q.l(b) What is meant by the lattice energy of an ionic compound? What quantities need to be
detennined and how are they used to calculate the lattice energy of an ionic compound 10
Q. The BF molecule is isoelectronic with carbon monoxide.
Construct an MO diagram.for the'BFmolecule. What assumption can be made in BF which makes the MO construction for this molecule much more straightforward than for CO?
Discuss the similarities and differences in the electronic structures of BF and CO in terms of cr and 1t bonds and nonbonding orbitals. What possible Lewis structures can be drawn _for BF and CO and which is the most reasonable for each species based
on your diagrams 5,5
Q. Explain the following observations on the basis of the kinetic theory of gases When NH3 gas is introduced at one end of a long tube while HCl gas is introduced
simultaneously at the other end, a ring of white ammonium chloride is observed to form in the·tube after a few minutes. This ring is closer to the HCl end of the tube
than the NH3 end.
(ii)· Nitrogen gas gets cooled on expansion at room-temperature whereas hydrogen gas gets warmer. Explain. 5,5
Q. Heisenberg's Uncertainty Principle (HUP)t as applied to the position, xt and momentumt of a particle can be given mathematically as deltaxdeltap>-h/4pie
Define the symbols Ax and 6.p .
Give an alternative non-mathematical statement of HUP.
(iii)For a particle trapped in a one-dimensional box of length the maximum value of deltax is L. ·calculate the minimum value of Ap for an electron trapped in a linear
molecule of length L x 10-9 and clearly state the units.
Starting from the de Broglierelation, lamda= show that the propagation of errorsimplies that
lamday=hdeltap/p2 lamda2lamdap/h,
and hence calculate the uncertainty in the wavelength of the electron in assuming that the wavelength 2L. Comment on your answer.
Q. A certain line in the spectrum of atomic hydrogen is associated with the electronic transition of the H atom from the sixth energy level· to the second energy level 2).
Indicate whether the H atom emits energy or absorbs energy during the transition. Justify your answer.
Calculate the wavelength, in nm, of the radiation associated with the spectral line.
Account for the observation that the amount of energy associated with the same electronic transition 6 n in the He+ ion is greater than that associated with the corresponding transition in the H atom. 10,5.
Q. Match the following rotational temperatures erot 0.164 0.082 9.12 0.0154 K to the four molecules I Cl, HI, I2 and IBr. Assign the. order of increasing rotational partition function for the four molecules at 100 K. Explain your reasoning. 20
Q. Five identical balloons are each filled to the same volume at 25°C and 1.0 atmosphere pressure with the pure gases CO2' 02, He, N2 and CH4.
Which balloon contains the greatest mass of gas Explain.
Compare the average kinetic energies of the gas molecules in the balloons. Explain.
Which balloon contains the gas that would be expected to deviate most from the
behaviour of an ideal gas Explain.
Twelve hours after being filled, all the balloons have decreased in size. Predict which balloon will be the smallest. Explain your reasoning.
1 Q.4(a) At 25°C, H202 decomposes according to the following equation
2h2o29aq)->2h2o(l)+o2(g) e=0.55v
What is meant by the standard electrode potential and how is it measured
Determine the value of the standard Gibbs energy change, ti.G0 for the reaction at 25°
Determine the value of the equilibrium constant, Ke• for the reaction at 25°
The standard reduction potential, E0 for the half reaction 4e-4 2 H20(l) has a value of 1.23 V. Using this information in addition to the information given above, determine the value of the standard reduction potential, E0 for the half reaction below
Q. Why is it usually a poor approximation to equate activities and concentrations for
ionic solutions
Outline the Debye-Htickel theory of dilute ionic solutions. Why is the central result of this theory described as .a limiting law
When and why can Debye-Htickel theory fail to describe th.. behaviour of ionic
solutions ..ccurately 10,5
SECTION-· B
Q. Account for each of the following observations
The complex [NiCl4)2-is attracted towards a magnetic field.
[PtCl2(NH3)2]has two isomers.
Q.5(b) In the reaction [CoCl3(NH3)3] NH3, only one isomer of the complex product is obtained. Is the initial complex cis or trans ?-Explain your answer. 10
Q.5(c) based on the rate co..stants given, indicate if the stepwise substitution reaction shown
below proceeds via an associative or dissociative· mechanism. Explain your answer clk
=3.0x10-7s-1
H2o k =3.0xl0-7s-1
Q. Explain why f-f transitions in the· electronic spectra of lanthanide complexes are weaker
than d.-d transitions in the corresponding spectra of transition metal complexes. 10
Q. The rea.ction 2N205 4N02 02 is first order with respect to -N205.
Using the axes below;complete the graph that represents the change in [N205] over time as the re..ction proceeds.
Describe how the graph in part' could be used to find the·reaction rate at a given time, t.
Considering the rate law and the graph in part descri..e how the value of the rate constant, could be determined.
If more N2o5were added to the reaction mixture at constant temperature, what would be the effect on the rate constant, k Explain.
<img images/1305-6-4.jpg'>
Q. The reaction catalyzed by an enzyme -recently purified from E. coli is.shown below
<img images/1305-6b.jpg'>
(i)Derive the Steady State. rate equation for the above reaction in the forward direction. assume initial rate .conditions (i.e.[P]t
0). Show all of your work and the necessary assumptions and equations.
(ii)Under what circumstances the kinetics are
(1)first-order substrate concentration
(2)Zero-order in substrate concentration
Q.7(a)For the complex
Draw a diagram to show the energy splitting of the 3d orbitals, indicating appropriate symmetry labels for the orbitals, the occupancy of the orbitals with electrons, and the crystal field splitting parameter.
Calculate the crystal-field stabilization energy in multiples of the crystal-field splitting
parameter. 15,5
Q. Give reasons why complexes of second and third row transition metals typically show a larger ligand field splitting than complexes of first row transition metals.
Explain the ways in which increased ligand-field splitting for second and third row transition metals affects the geometry of four-coordinate Pt(II) complexes compared with the geometry of four-coordinate Ni(II) complexes. I
Q.8(a) Write brief notes on the following
Ferredoxins
Super-acids. 10,10
Compare the solvent behaviour of water and liquid ammonia. How does ammonium hydroxide behave in liquid ammonia
The relaxation-time for a reversible first-order reaction is 1 x 10-5 and the equilibrium constant is 1 x 103 • Find K1 and K_1 • 10,10
Allempts of questions shall be counted chronological order. Unless struck off. atle_mpl of a question shall
be counted even if allempted partly. Any page or portion of the page left· blank in the Answer B90k must
he clearly struck off.
All questions carry equal f1U!l'/cs. The number of marks carried by a question/part is indicated against it.
Answers must be written in ENGUSH only.
Unless otherwis.. .mentioned, symbols and notations have their usual. standard meanings.
Assume suitable data, if necessary and indicate' the same clearly.
Neat sketches may be drawn, wherever required
SECTION-A
6.626, x ur34 JS; kg 1.38 x J0-23 J 8.314 J...1 mo1-1; rr 3.14;
RH 10973731.6 c 3 Ja8
· Q. 1. Answer briefly au the parts 10X4=40
selecting at least ONE question from each of the two Sections A and B.
Allempts of questions shall be counted chronological order. Unless struck off. atle_mpl of a question shall
be counted even if allempted partly. Any page or portion of the page left· blank in the Answer B90k must
he clearly struck off.
All questions carry equal f1U!l'/cs. The number of marks carried by a question/part is indicated against it.
Answers must be written in ENGUSH only.
Unless otherwis.. .mentioned, symbols and notations have their usual. standard meanings.
Assume suitable data, if necessary and indicate' the same clearly.
Neat sketches may be drawn, wherever required
SECTION-A
6.626, x ur34 JS; kg 1.38 x J0-23 J 8.314 J...1 mo1-1; rr 3.14;
RH 10973731.6 c 3 Ja8
· Q. 1. Answer briefly au the parts 10X4=40
jc-HENT-N-BGDLA I
CHEMISTRY
Paper-I
Inme Allowed Three Hours I
Maximum Marks 100 j
· QUESTION PAPER SPECIFIC INSTRUCTIONS
Plet1se read each of the following instructions carefully be/ ore aJtempting questions
There are EIGHT questions in all, out of which FIVE are to be attempted.
Question nos. J and S are compulsory. Out of the remaining SIX questions, THREE. are to be attempted
Q. A Phase Rule can be written as F C where F is the number of degrees of freedom, P is the number of phases and C is the number of components.
Define the tenns degree freedom; phase and component. ·
Use the Phase Rule to show why, when plotting a phase diagram of a 2-component system, it is necessary to fix a yariable (usually volume).
6,4
Q.l(b) What is meant by the lattice energy of an ionic compound? What quantities need to be
detennined and how are they used to calculate the lattice energy of an ionic compound 10
Q. The BF molecule is isoelectronic with carbon monoxide.
Construct an MO diagram.for the'BFmolecule. What assumption can be made in BF which makes the MO construction for this molecule much more straightforward than for CO?
Discuss the similarities and differences in the electronic structures of BF and CO in terms of cr and 1t bonds and nonbonding orbitals. What possible Lewis structures can be drawn _for BF and CO and which is the most reasonable for each species based
on your diagrams 5,5
Q. Explain the following observations on the basis of the kinetic theory of gases When NH3 gas is introduced at one end of a long tube while HCl gas is introduced
simultaneously at the other end, a ring of white ammonium chloride is observed to form in the·tube after a few minutes. This ring is closer to the HCl end of the tube
than the NH3 end.
(ii)· Nitrogen gas gets cooled on expansion at room-temperature whereas hydrogen gas gets warmer. Explain. 5,5
Q. Heisenberg's Uncertainty Principle (HUP)t as applied to the position, xt and momentumt of a particle can be given mathematically as deltaxdeltap>-h/4pie
Define the symbols Ax and 6.p .
Give an alternative non-mathematical statement of HUP.
(iii)For a particle trapped in a one-dimensional box of length the maximum value of deltax is L. ·calculate the minimum value of Ap for an electron trapped in a linear
molecule of length L x 10-9 and clearly state the units.
Starting from the de Broglierelation, lamda= show that the propagation of errorsimplies that
lamday=hdeltap/p2 lamda2lamdap/h,
and hence calculate the uncertainty in the wavelength of the electron in assuming that the wavelength 2L. Comment on your answer.
Q. A certain line in the spectrum of atomic hydrogen is associated with the electronic transition of the H atom from the sixth energy level· to the second energy level 2).
Indicate whether the H atom emits energy or absorbs energy during the transition. Justify your answer.
Calculate the wavelength, in nm, of the radiation associated with the spectral line.
Account for the observation that the amount of energy associated with the same electronic transition 6 n in the He+ ion is greater than that associated with the corresponding transition in the H atom. 10,5.
Q. Match the following rotational temperatures erot 0.164 0.082 9.12 0.0154 K to the four molecules I Cl, HI, I2 and IBr. Assign the. order of increasing rotational partition function for the four molecules at 100 K. Explain your reasoning. 20
Q. Five identical balloons are each filled to the same volume at 25°C and 1.0 atmosphere pressure with the pure gases CO2' 02, He, N2 and CH4.
Which balloon contains the greatest mass of gas Explain.
Compare the average kinetic energies of the gas molecules in the balloons. Explain.
Which balloon contains the gas that would be expected to deviate most from the
behaviour of an ideal gas Explain.
Twelve hours after being filled, all the balloons have decreased in size. Predict which balloon will be the smallest. Explain your reasoning.
1 Q.4(a) At 25°C, H202 decomposes according to the following equation
2h2o29aq)->2h2o(l)+o2(g) e=0.55v
What is meant by the standard electrode potential and how is it measured
Determine the value of the standard Gibbs energy change, ti.G0 for the reaction at 25°
Determine the value of the equilibrium constant, Ke• for the reaction at 25°
The standard reduction potential, E0 for the half reaction 4e-4 2 H20(l) has a value of 1.23 V. Using this information in addition to the information given above, determine the value of the standard reduction potential, E0 for the half reaction below
Q. Why is it usually a poor approximation to equate activities and concentrations for
ionic solutions
Outline the Debye-Htickel theory of dilute ionic solutions. Why is the central result of this theory described as .a limiting law
When and why can Debye-Htickel theory fail to describe th.. behaviour of ionic
solutions ..ccurately 10,5
SECTION-· B
Q. Account for each of the following observations
The complex [NiCl4)2-is attracted towards a magnetic field.
[PtCl2(NH3)2]has two isomers.
Q.5(b) In the reaction [CoCl3(NH3)3] NH3, only one isomer of the complex product is obtained. Is the initial complex cis or trans ?-Explain your answer. 10
Q.5(c) based on the rate co..stants given, indicate if the stepwise substitution reaction shown
below proceeds via an associative or dissociative· mechanism. Explain your answer clk
=3.0x10-7s-1
H2o k =3.0xl0-7s-1
Q. Explain why f-f transitions in the· electronic spectra of lanthanide complexes are weaker
than d.-d transitions in the corresponding spectra of transition metal complexes. 10
Q. The rea.ction 2N205 4N02 02 is first order with respect to -N205.
Using the axes below;complete the graph that represents the change in [N205] over time as the re..ction proceeds.
Describe how the graph in part' could be used to find the·reaction rate at a given time, t.
Considering the rate law and the graph in part descri..e how the value of the rate constant, could be determined.
If more N2o5were added to the reaction mixture at constant temperature, what would be the effect on the rate constant, k Explain.
<img images/1305-6-4.jpg'>
Q. The reaction catalyzed by an enzyme -recently purified from E. coli is.shown below
<img images/1305-6b.jpg'>
(i)Derive the Steady State. rate equation for the above reaction in the forward direction. assume initial rate .conditions (i.e.[P]t
0). Show all of your work and the necessary assumptions and equations.
(ii)Under what circumstances the kinetics are
(1)first-order substrate concentration
(2)Zero-order in substrate concentration
Q.7(a)For the complex
Draw a diagram to show the energy splitting of the 3d orbitals, indicating appropriate symmetry labels for the orbitals, the occupancy of the orbitals with electrons, and the crystal field splitting parameter.
Calculate the crystal-field stabilization energy in multiples of the crystal-field splitting
parameter. 15,5
Q. Give reasons why complexes of second and third row transition metals typically show a larger ligand field splitting than complexes of first row transition metals.
Explain the ways in which increased ligand-field splitting for second and third row transition metals affects the geometry of four-coordinate Pt(II) complexes compared with the geometry of four-coordinate Ni(II) complexes. I
Q.8(a) Write brief notes on the following
Ferredoxins
Super-acids. 10,10
Compare the solvent behaviour of water and liquid ammonia. How does ammonium hydroxide behave in liquid ammonia
The relaxation-time for a reversible first-order reaction is 1 x 10-5 and the equilibrium constant is 1 x 103 • Find K1 and K_1 • 10,10