Exam Details
| Subject | chemistry | |
| Paper | paper 2 | |
| Exam / Course | combined geo-scientist and geologist | |
| Department | ||
| Organization | union public service commission | |
| Position | geologist | |
| Exam Date | 2016 | |
| City, State | central government, |
Question Paper
l.
What is virial equation of state for real gases ?Express van der Waals equation in the form o f
virial equation. Discuss the physical significance of virial coefficients.
A capillary tube of radius 0.001 cm is inclined at
an angle of 45° to the surface of the liquid. The
liquid wets the wall of the tube. Calculate the
distance along the capillary to the miniscus of of the liquid if the density of the liquid is 0.85 g and the surface tension is 36 dynes
The net entropy of the Universe increases.
X rays are used for diffraction by crystals.
Applying the law of equipartition of energy,
estimate the energy of H2 molecule assuming that
all the degrees of freedom are excited and
contribute towards the energy of the molecule. Give
the statement of the law.
Calculate the fall in temperature of He gas initially at temperature IS°C when it is suddenly expanded at temperature 15°C when it is suddenly expanded to eight times its volume. (Given γ
Deduce the equation to show the variation of Kp
with temperature and show that KP is independent
of Pressure.
Calculate the pH of 0.01 M NH4C1 in water at 25°C. pKb for NH4OH is 4.74. Ion product of water is 10^14
Explain the term reverse-osmosis.
The following data were obtained for the reaction
A B products. Derive the rate law.
src='./qimages/7983-1i.jpg'>
130 ml o f N 2 (corrected to 0°C and 1 bar pressure) was required to form a monolayer on a solid.
Calculate the surface area of the solid. Cross sectional area of is 16.2 A^2.
A current of 800 mA was passed through a dilute
solution of CuSO. for 20 minutes. What are the products liberated at anode and cathode Find the
amount
If sufficient energy is absorbed by an atom an
electron can be lost by the atom and a positive ion formed.The amount of energy required is called
the ionization energy. In the hydrogen atom, the
ionization energy is that required to change the
electron from n 1 to n ∞. Calculate the
ionization energy (in k.J for He+ ions. Is
the ionization energy of the He+ ion more or less
than that of hydrogen
Using a radiation source of 250 W at 250 nm, a
compound was irradiated for 90 mins. 40% of the
light was reflected off and the rest was absorbed
by the compound. After irradiation, 0.02 moles of
the compound was found to have decomposed.
Calculate the quantum yield for the decomposition.
Show that the function A sin for a particle
in a one-dimensional box of length L is not an
in a one-dimensional box o f length L is not a eigenfunction of the momentum operator,
Px but it is so of p^2. Discuss the
significance of the result.
Discuss the molecular orbitals and the various
electronic transitions possible in formaldehyde,
CH20. Draw an appropriate energy level diagram
displaying these transitions.
By predicting the appearance of its proton NMR
spectrum, show how each member of the following
pair of isomers may be distinguished
1-dim ethoxyethane, and
2-dim ethoxyethane.
SECTION-O
2. A space capsule is filled with neon gas at 1.O atm and
290 K. The gas effuses through a pinhole into outer
space at such a rate that the pressure drops by 0.30 torr/s.
If the capsule were filled with Niil al the same temperature and pressure, what would be the
pressure drop
When the capsule was filled with 30.0 mol
helium, 20 mol oxygen 50 mol nitrogen
at the total pressure of 1.O atm and at the
temperature of 290 what would be the raie of
pressure drop
3. Define chemical potential. Deduce the Gibbs-Duhem
equation and show that the variation of chemical
potential affects the value of other component.
4. Whet do you mean by an orthorhombic crystal Show
that for an orthorhombic lattice, the distance (dhkl) between two crystal planes defined by is given by
1/dhkl^2
b and e are the length of the edges.
k1 k2
5. For two parallel reactions B and A
find equations for the concentration of B and C as
a function of time. Represent graphically.
6. For the dissociative chemisorption of gaseous A2 at
gaseous A 2 at pressure P A2 2 A derive equation for the fractional surface coverage using Langmuir theory.
7. A series of photophysical measurements are carried out
on an aqueous solution of compound X. The fluorescence lifetime is 20 ns and the intersystem
crossing (S1 to T1 quantum yield is 0.4. The
phosphorescence quantum yield is O.1 and the
phosphorescence lifetime is 1s. No photochemical
decomposition occurs. Draw a Jablonskii energy level
diagram showing the ground and first excited
singlet electronic states and the lowest triplet
electronic state for molecule X. Using the photophysicaJ
information provided above, indicate in your diagram
all the radiative and non-radiative processes operating
between these states following absorp1ion of light.
8. The harmonic oscillator model provides a means of
interpreting the vibrations of small molecules. When
applied to a homonuclear diatomic molecule made up
of atoms with mass m. the model yields vibrational
vibrational energy levels given by
En 1/2)hv
where n ....... is the vibrational quantum
number, k is the force constant of the
chemical bond, and 1,1 m is the reduced mass.
Sketch an energy level diagram for the harmonic
oscillator. showing the first four energy levels in units of hv.
The ground state weve functicn for the harmonic
oscillator is given by
wo α exp
where x is the deviation from the equilibrium bond
separation and ß sqrt(µk)/A
i . Sketch the wave function and then determine the most probable wave function and then determine the
value of x and the average value of x.
The vibrational wave number of diatomic chlorine,
35C12, is 559.71 cm^-1. Calculate the force constant for the Cl-Cl bond. Assume that the atomic weight
9. Explain concisely what is meant by nuclear spin- spin coupling using the 1H NMR spectrum. of
CH Br2 CHO as an example. Explain how spin- spin coupling arises in this example.
What is meant by the term coupling constant
1O. Calculate the energy in Joule to disperse one
spherical drop of radius 3 .O mm into spherical
drops of radius 3.0 x mm if the surface tension of the drop is 72.8 dynes
Deduce the expression for the work done change
of internal energy ΔU and change of enthalpy ΔH
for the reversible expansion from volume V1 to
volume V2 for a van der Waals gas.
11. Define zeta potential. Explain its significance. Discuss
one method of determining zeta potential.
12. HI molecules absorb radiation o f wavelength
2309.5 cm^-1. Calculate the accompanying
change in internal energy of an HI molecule
in Joule.
Determine the number of norm al vibrational
modes of each of the following molecules
hydrogen chloride; hydrogen cyanide, ethene,
benzene.
Deduce which of the following molecules will
show a microwave (rotational) spectrum and
explain your answer
What are Rayleigh, Stokes and Anti-Stokes
lines? Is the intensity of Stokes lines different from that of the anti-Stokes lines Explain.
Sketch the normal modes of vibration of C02
and explain which of these are Raman and
which are IR active.
13. In the rotational spectrum of a diatomic molecule, the firs t three transitions are observed at
17.68 35.36 and 53.04 cm^-1.
Calculate the rotational constant, B. of the
molecule.
Predict the wave number of the transition from
J 4 to J 5.
W hat other inform action would you need to
be able 10 calculate the bond length of the
molecule? Explain your answer.
Calculate the wavelength of light that an electron
in a 1 x m box must absorb to change its
quantum number from 1 to 2. In what region of
the spectrum would this be found
A sample of a diene in methanol in a 1.OO cm cell
shows an absorbance of 0.65 at 242.5 nm. What
is the concentration of the diene The molar
absorptivity at this wave length is 13,100.
What is virial equation of state for real gases ?Express van der Waals equation in the form o f
virial equation. Discuss the physical significance of virial coefficients.
A capillary tube of radius 0.001 cm is inclined at
an angle of 45° to the surface of the liquid. The
liquid wets the wall of the tube. Calculate the
distance along the capillary to the miniscus of of the liquid if the density of the liquid is 0.85 g and the surface tension is 36 dynes
The net entropy of the Universe increases.
X rays are used for diffraction by crystals.
Applying the law of equipartition of energy,
estimate the energy of H2 molecule assuming that
all the degrees of freedom are excited and
contribute towards the energy of the molecule. Give
the statement of the law.
Calculate the fall in temperature of He gas initially at temperature IS°C when it is suddenly expanded at temperature 15°C when it is suddenly expanded to eight times its volume. (Given γ
Deduce the equation to show the variation of Kp
with temperature and show that KP is independent
of Pressure.
Calculate the pH of 0.01 M NH4C1 in water at 25°C. pKb for NH4OH is 4.74. Ion product of water is 10^14
Explain the term reverse-osmosis.
The following data were obtained for the reaction
A B products. Derive the rate law.
src='./qimages/7983-1i.jpg'>
130 ml o f N 2 (corrected to 0°C and 1 bar pressure) was required to form a monolayer on a solid.
Calculate the surface area of the solid. Cross sectional area of is 16.2 A^2.
A current of 800 mA was passed through a dilute
solution of CuSO. for 20 minutes. What are the products liberated at anode and cathode Find the
amount
If sufficient energy is absorbed by an atom an
electron can be lost by the atom and a positive ion formed.The amount of energy required is called
the ionization energy. In the hydrogen atom, the
ionization energy is that required to change the
electron from n 1 to n ∞. Calculate the
ionization energy (in k.J for He+ ions. Is
the ionization energy of the He+ ion more or less
than that of hydrogen
Using a radiation source of 250 W at 250 nm, a
compound was irradiated for 90 mins. 40% of the
light was reflected off and the rest was absorbed
by the compound. After irradiation, 0.02 moles of
the compound was found to have decomposed.
Calculate the quantum yield for the decomposition.
Show that the function A sin for a particle
in a one-dimensional box of length L is not an
in a one-dimensional box o f length L is not a eigenfunction of the momentum operator,
Px but it is so of p^2. Discuss the
significance of the result.
Discuss the molecular orbitals and the various
electronic transitions possible in formaldehyde,
CH20. Draw an appropriate energy level diagram
displaying these transitions.
By predicting the appearance of its proton NMR
spectrum, show how each member of the following
pair of isomers may be distinguished
1-dim ethoxyethane, and
2-dim ethoxyethane.
SECTION-O
2. A space capsule is filled with neon gas at 1.O atm and
290 K. The gas effuses through a pinhole into outer
space at such a rate that the pressure drops by 0.30 torr/s.
If the capsule were filled with Niil al the same temperature and pressure, what would be the
pressure drop
When the capsule was filled with 30.0 mol
helium, 20 mol oxygen 50 mol nitrogen
at the total pressure of 1.O atm and at the
temperature of 290 what would be the raie of
pressure drop
3. Define chemical potential. Deduce the Gibbs-Duhem
equation and show that the variation of chemical
potential affects the value of other component.
4. Whet do you mean by an orthorhombic crystal Show
that for an orthorhombic lattice, the distance (dhkl) between two crystal planes defined by is given by
1/dhkl^2
b and e are the length of the edges.
k1 k2
5. For two parallel reactions B and A
find equations for the concentration of B and C as
a function of time. Represent graphically.
6. For the dissociative chemisorption of gaseous A2 at
gaseous A 2 at pressure P A2 2 A derive equation for the fractional surface coverage using Langmuir theory.
7. A series of photophysical measurements are carried out
on an aqueous solution of compound X. The fluorescence lifetime is 20 ns and the intersystem
crossing (S1 to T1 quantum yield is 0.4. The
phosphorescence quantum yield is O.1 and the
phosphorescence lifetime is 1s. No photochemical
decomposition occurs. Draw a Jablonskii energy level
diagram showing the ground and first excited
singlet electronic states and the lowest triplet
electronic state for molecule X. Using the photophysicaJ
information provided above, indicate in your diagram
all the radiative and non-radiative processes operating
between these states following absorp1ion of light.
8. The harmonic oscillator model provides a means of
interpreting the vibrations of small molecules. When
applied to a homonuclear diatomic molecule made up
of atoms with mass m. the model yields vibrational
vibrational energy levels given by
En 1/2)hv
where n ....... is the vibrational quantum
number, k is the force constant of the
chemical bond, and 1,1 m is the reduced mass.
Sketch an energy level diagram for the harmonic
oscillator. showing the first four energy levels in units of hv.
The ground state weve functicn for the harmonic
oscillator is given by
wo α exp
where x is the deviation from the equilibrium bond
separation and ß sqrt(µk)/A
i . Sketch the wave function and then determine the most probable wave function and then determine the
value of x and the average value of x.
The vibrational wave number of diatomic chlorine,
35C12, is 559.71 cm^-1. Calculate the force constant for the Cl-Cl bond. Assume that the atomic weight
9. Explain concisely what is meant by nuclear spin- spin coupling using the 1H NMR spectrum. of
CH Br2 CHO as an example. Explain how spin- spin coupling arises in this example.
What is meant by the term coupling constant
1O. Calculate the energy in Joule to disperse one
spherical drop of radius 3 .O mm into spherical
drops of radius 3.0 x mm if the surface tension of the drop is 72.8 dynes
Deduce the expression for the work done change
of internal energy ΔU and change of enthalpy ΔH
for the reversible expansion from volume V1 to
volume V2 for a van der Waals gas.
11. Define zeta potential. Explain its significance. Discuss
one method of determining zeta potential.
12. HI molecules absorb radiation o f wavelength
2309.5 cm^-1. Calculate the accompanying
change in internal energy of an HI molecule
in Joule.
Determine the number of norm al vibrational
modes of each of the following molecules
hydrogen chloride; hydrogen cyanide, ethene,
benzene.
Deduce which of the following molecules will
show a microwave (rotational) spectrum and
explain your answer
What are Rayleigh, Stokes and Anti-Stokes
lines? Is the intensity of Stokes lines different from that of the anti-Stokes lines Explain.
Sketch the normal modes of vibration of C02
and explain which of these are Raman and
which are IR active.
13. In the rotational spectrum of a diatomic molecule, the firs t three transitions are observed at
17.68 35.36 and 53.04 cm^-1.
Calculate the rotational constant, B. of the
molecule.
Predict the wave number of the transition from
J 4 to J 5.
W hat other inform action would you need to
be able 10 calculate the bond length of the
molecule? Explain your answer.
Calculate the wavelength of light that an electron
in a 1 x m box must absorb to change its
quantum number from 1 to 2. In what region of
the spectrum would this be found
A sample of a diene in methanol in a 1.OO cm cell
shows an absorbance of 0.65 at 242.5 nm. What
is the concentration of the diene The molar
absorptivity at this wave length is 13,100.