TIFR GS 2025 Question Paper Chemistry

FOR TIFR GS EXAM PREPARATION

TIFR GS 2025
Question Paper ·
Chemistry
EXAM YEAR TYPE SUBJECT

TIFR GS 2025 Question Paper Chemistry

Notes · Sample Papers · Previous Year Papers · Mock Tests

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Tata Institute of Fundamental Research
Answers for Chemistry GS2025 Written Examination

Examination Date: 08 December 2024
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c. o(The correct answers are highlighted in yellow) m .co
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a of a 𝐾 X-ray from an element having atomic number Z is:
1. Thelenergy
g ag
a α

(𝐾α) = (10. 2 )( − 1)
2

Which element has a 𝐾α X-ray line with a wavelength of 0.180 nm?
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A) Ti ( = 22) s e
B) Co ( = 27)
g la
C) Zn ( = 30) a
D) Cu ( = 29)

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a For more Question Papers, Sample Papers, Notes & Syllabus visit Page 1 of 41

2. Which of these reactions are spontaneous in gas phase?

i) Xe + He+ → Xe+ + He
ii) Si + Cl+ → Si+ + Cl
iii) F- + I → F + I-
iv) Br- + Ar → Br + Ar-

A) iii and iv

B) i and ii

C) i, ii and iv

D) only ii
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3. Atomic nuclear diameter is approximately 5 femtometer.aWhat would be the approximate
velocity of an electron, if it was part of a nucleus with the weight of the electron being
9.109 × 10-31 kg?

(Note: c = velocity of light in vacuum)

A) 40 c m
B) c m .co
C) c/20
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D) 2 c
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a

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a For more Question Papers, Sample Papers, Notes & Syllabus visit Page 3 of 41

4. The reactant (R) can convert into products P1 or P2 as can be seen in reaction profile
shown below. If you want R to be converted mostly into P1 you will:

A) Carry out the reaction at low temperature so that P1 is the major product for
thermodynamic reasons.
B) Carry out the reaction at low temperature (in a limited time) so that P1 is the major
product for kinetic reasons.
C) Carry out the reaction at high temperature so that P1 is the major product for
thermodynamic reasons.
D) Carry out the reaction at high temperature (in a limited time) so that P1 is the major
product for kinetic reasons.
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m .co s em
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5. Among the resonance forms given below, which one is theamost stable one?

A) B) C) D)
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a

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a For more Question Papers, Sample Papers, Notes & Syllabus visit Page 5 of 41

6) Which of functions best represents the graph shown here:

( )
−
−
A) −
+

B) ( ) 1+
1
−

C) ( )
−
−
−
+

D) ( ) +1
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m .co s e m
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a
7. The derivative of ( ) = ( )1+
1
− (with respect to ) is:

A) ( )
B) 1 − ( )
C) (1 − ( )) ( )
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( ) om .co
1
D)
c m
1− ( )

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ag

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a For more Question Papers, Sample Papers, Notes & Syllabus visit Page 7 of 41

8. Predict the major product from the following reaction.

A) B) C) D)

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m .co s em
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9. Equation of state of a system in canonical ensemble (N, V,aβ) is given by:

(N is the number of particles, V is the volume, T is the temperature, Q is the partition
function, β = 1/(kBT), and < > means the ensemble average of pressure)

A) < > =
1
β ( δ
δ ) ,β

( ) m
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1 δ
B) < > =
o m δβ
,
m
C) < > =.c ( ) e
1 δ

e m 2 δβ
l as
s
D) < la> =
,

ag
g ( ) 1 δ

a
2 δ
β ,β

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a For more Question Papers, Sample Papers, Notes & Syllabus visit Page 9 of 41

10. The number of stereoisomer(s) of trans-[CoCl2(triethylenetetramine)]Br is(are)

A) One B) Two C) Three D) Four
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m .co s e m
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a
11. Ensemble average of Gibbs entropy (< >) is given by:

A) < > = − Σ
B) < > = Σ

C) < > = ( )
m
D) < > =
m (− )
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m .co s e m
e
is Boltzman constant and
s
is probability of occurrence of state with energy
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a For more Question Papers, Sample Papers, Notes & Syllabus visit Page 11 of 41

12. Energy of a free electron plotted as a function of its momentum will be:

A) Hyperbolic
B) Oscillatory
C) Parabolic
D) Linear
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m .co s em
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13. The catalyst involved in carrying out the cross metathesisaof 1–butene to give ethylene
and 3–hexene is:

A) RuCl2(=CHPh)(PCy3)2 (Cy is cyclohexyl)

B) Na2PdCl4

C) Co2(CO)8, H2
m
D) RhCl(PPh3)3
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a For more Question Papers, Sample Papers, Notes & Syllabus visit Page 13 of 41

14. Ultimate spatial resolution of a microscope is related to the wavelength of the probe beam
as:

A) λ
B) 1/λ
C) λ2
D) (λ)1/2
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a ] (en = ethylene diamine),
15. Regarding the metal complexes [Co(NH ) ] and [Co(en)
3 6
3+
3
3+

which of the following is true?

A) Both complexes have the same stability
B) Stability of [Co(NH3)6]3+ is higher than [Co(en)3]3+
C) Stability of [Co(NH3)6]3+ is lower than [Co(en)3]3+
D) No conclusion can be made regarding the stability of the complexes
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a For more Question Papers, Sample Papers, Notes & Syllabus visit Page 15 of 41

16. In a spectroscopic measurement it is found that the spectrum is broadened with Doppler
broadening having the dominant contribution. Which of the following functions will best
(
represent this spectral lineshape υ − υ0 ? )
(υ0 is the resonance frequency of the corresponding spectroscopic transition)

A) [− (υ − υ0)]; is a constant
B) 1/[
2
− (υ − υ0)2]; is a constant
C) exp ⎡⎢−
⎣ (υ − υ0)2⎤⎥⎦ ; is a constant

(
D) υ − υ0 )2
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a )(Cl)(NO )], where Py is
17. Consider the square planar platinum (II) complex [Pt(Py)(NH 3 2
pyridine. Based on the given facts:
1. The trans effect order: NO2- > Cl- > Py > NH3
2. N NMR chemical shift of coordinated NH3: δ = -70 ppm
15

3. 15
N NMR chemical shift of coordinated NO2: δ = +140 ppm (when N-bonded),
δ = -20 ppm (when O-bonded)
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Which of the following statements is correct?
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The major product of the reaction of this complex with excess NH will haveg l a
g l
A)a a 3

a B) The N NMR spectrum of the complex will show two signals: one at -70 ppm
Cl trans to NH .
-
3
15

and another at +140 ppm.
C) The complex is optically active.
D) Treating the complex with AgNO3 will result in immediate and complete
precipitation of AgCl.

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a For more Question Papers, Sample Papers, Notes & Syllabus visit Page 17 of 41

18. A solution of two non-interacting metal complexes, X and Y, are taken in a cuvette with
path length of 1 cm. The concentration of X is one micromolar (1 µM) and the concentration
of Y is two micromolar (2 µM). The molar extinction coefficients for complexes X and Y at
500 nm are εX = 1 × 105 M-1 cm-1 and εY = 2 × 105 M-1 cm-1, respectively. The absorbance of
the solution at 500 nm is:

A) 1
B) 0.3
C) 0.4
D) 0.5
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a the H-NMR peak for the
19. Predict the approximate chemical shift and multiplicity of 1

proton at position ‘g’ marked in the structure shown below.

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A) 3 ppm and double-doublet
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B) 3 ppm and triplet
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la ag
C) 5.5 ppm and double-doublet
g
aD) 5.5 ppm and triplet

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ag For more Question Papers, Sample Papers, Notes & Syllabus visit Page 19 of 41

20. How many vibrational and rotational degrees of freedom does the following molecule
have?

A) 30, 2
B) 12, 3
C) 30, 3
D) 12, 2
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a can theoretically fold into an
21. A protein chain with even a modest number of amino acids
astronomically large number of different conformations. If a protein were to explore each
possible conformation sequentially, even at an incredibly fast rate, it would take far longer
than the age of the universe to reach its native, functional state. However, consider the
following simple theoretical model for protein folding:

i) The protein is made up of only 10 amino acids
ii) Each amino acid can exist in one of two states: one correctly and one incorrectly folded
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iii) In each second, one amino acid is randomly chosen
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iv) If the amino acid is in the incorrectly folded state, it switches to the correctly folded state
s e m
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v) If the amino acid is in the correctly folded state, nothing happens during that second
g l a
g l
Starting from aall amino acids in the incorrectly folded state, approximately how long will a
it
take on a
an average for such a protein to fold correctly?

A) 10 seconds
B) 30 seconds
C) 30 minutes
D) 30 hours
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a For more Question Papers, Sample Papers, Notes & Syllabus visit Page 21 of 41

22. What would you obtain if you tried the following coupling reaction in a laboratory
setting?

A)

B)

C)

D) Mixture of polymers
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a + phosphate) is -28 kJ/mole.
23. The ΔG° (at 300 K) for the hydrolysis of ATP (ATP → ADP
In cellular cytoplasm, the concentration of ATP, ADP, and phosphate are buffered at 10 mM,
10 μM and 10 mM, respectively. This ATP hydrolysis is coupled to an enzymatic reaction (R)
that has a ΔG of +112 kJ/mol in absence of the enzyme. What is the minimum number of
molecules of ATP which must be hydrolyzed in order to have a thermodynamically favorable
net reaction (ATP hydrolysis + R)?

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A) 1
B) 2
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s e l a
ag
C) 4
g l a
D) Cannot be determined from the given data
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a For more Question Papers, Sample Papers, Notes & Syllabus visit Page 23 of 41

24. Imagine that a system is in a state |α⟩. An observation is made on this system, where the
^ ^
operator is represented by and the final state is | ⟩. The eigenstates of are represented by
{| ⟩}. Which of the following statements is true?

2
A) The probability of obtaining | ⟩ as | ⟩ is |⟨α⟩|

2

B) The probability of obtaining | ⟩ as | ⟩ is | ∑ ⟨α⟩|

C) The probability of obtaining | ⟩ as | ⟩ is |⟨α⟩|

D) | ⟩ can be different from any of { | ⟩}
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25. Predict the product of the following reaction. a

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a

A)
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s e
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a

B)

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s e g l a
g la C) a
a

D)
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g la ag
a For more Question Papers, Sample Papers, Notes & Syllabus visit Page 25 of 41

26. Consider the quantum mechanical problem of a particle inside a 1-dimensional box where
the height of the well can be either infinite or finite ( 0 < ∞). Which of the following
statement is correct?

A) All the eigenstates of the infinitely high box are lower in energy than the
corresponding states in the finite counterpart
B) All the eigenstates of the infinitely high box are higher in energy than the
corresponding states in the finite counterpart

C) The eigenfunctions are different but the energies remain the same

D) The eigenstates can be higher or lower depending on the height of the well
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a
27. Consider the quantum mechanical problem of a particle inside a 1-D box with infinitely
high walls. Which of the following statements is correct?

A) There is a well-defined kinetic energy, , associated with each state and hence,
2
there is also definite momentum, , since, classically, = /(2 )
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ℎ
B) The standard deviation of momentum in the state is 2 , where is the
e m
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energy in the
ℎ

l as
a s
lexpectation ag
ag
C) The value of momentum in each state is positive

ℎ
D) The standard deviation of momentum in the state is 2 , where is the
ℎ
energy in the eigenstate

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ag For more Question Papers, Sample Papers, Notes & Syllabus visit Page 27 of 41

28. The iodine test gives a blue color due to

A) Starch – 2 complex

−
B) Presence of 3

C) Decomposition of starch

−
D) Starch – 3 complex
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a
29. For a system with indistinguishable particles and a normalized wavefunction ψ,
the probability of finding a single particle at position r1 is given as,

( 1) = ∫ 2 3
... |ψ( 1 2..
2
)| such that the integral over P reduces to the

number of particles, i.e. ∫ ( 1) = . In a similar fashion, how would you m
.co
1
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define the probability of finding two particles, one at position r1 and the other at r2.
s e m
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aA) ( , ) = ∫
1 2 3
... |ψ( 1 2 3.. )|
2

B) ( 1, 2) = ( − 1)/2∫ 3
... |ψ( 1 2 3.. )|
2

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( 1, 2) = ( − 1) ∫ s em|ψ( 2

la
C) 3
... 1 2 3
.. )|

ag
D) ( 1, 2) = ( 1)× ( 2)

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ag For more Question Papers, Sample Papers, Notes & Syllabus visit Page 29 of 41

30. Consider the following functions:
−
−
( )= 2

−
+
( )= 2

Which of the plots shown below correctly represents the above functions?

A)

B)

C)
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D) a

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a
Correct Answer: D

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a

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a For more Question Papers, Sample Papers, Notes & Syllabus visit Page 31 of 41

31. A typical lithium-ion battery (4 Volt output) in a phone, powered using a 5-Watt charger
can fully charge in 1.5 hours. While using the phone if the average current drawn is 50 mA
and a with a single charging the phone runs for about 20 hours after which the battery fully
drains, which of the following is a reasonable estimate of the efficiency of the phone battery?
(efficiency = output power delivered / power consumed in charging)

A) 74%
B) 23%
C) 53%
D) 84%
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a 7-dehydrocholesterol. Predict
32. Vitamin D3 precursor pre-cholecalciferol is produced from
the reaction condition used for the transformation.

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aA) acid
B) base
C) heat
D) light

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a For more Question Papers, Sample Papers, Notes & Syllabus visit Page 33 of 41

33. D2O is heated using an electric heater in contact with it under a pressure of 1.0 atm such
that it boils. When an electric current of 0.8 A from a 10 V supply is passed for 210 seconds
it is observed that 0.8 g of D2O is vaporized. Which of the following values of molar enthalpy
and molar internal energy changes at the boiling point (374 K) are correct?

A) ΔHm = +42 kJ/mol, ΔUm = +39 kJ/mol
B) ΔHm = +11 kJ/mol, ΔUm = 0 kJ/mol
C) ΔHm = +39 kJ/mol, ΔUm = +42 kJ/mol
D) ΔHm = −42 kJ/mol, ΔUm = −39 kJ/mol
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34. Ground state wavefunction of the hydrogen atom can bea
written in the following form:

ψ( ) ∝ (− / 0)

And that for He+ ion can be written as:

m
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Φ( ) ∝ (− 2 / 0)
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a of probabilities (expressed in percentage) of finding the electron in a smallg
g as a cube with dimensions 1 × 10 m at = and at the nucleus for botha
l
What is the ratio
volumeashaped -12
0
cases?

A) H-atom: 36%, He+ ion: 5%
B) H-atom: 23%, He+ ion: 8%
C) H-atom: 14%, He+ ion: 2%
D) H-atom: 11%, He+ ion: 14 %

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a For more Question Papers, Sample Papers, Notes & Syllabus visit Page 35 of 41

35. Arrange the following molecules in decreasing rate of solvolysis.

A) A > B > C
B) B > C > A
C) C > A > B
D) C > B > A
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a ℎ( ) defined below:
36. Which of the following plots correctly represents the function

( )
2
−5 +6 − /5
ℎ( ) = −1

A)

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g l a ag
a
B)

m
m.co
s e
C) g la
a

m
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.co
D)
e m
e m l as
las ag
ag

Correct Answer: C

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37. Which of the following statements is correct?

A) A is chiral and B is achiral
B) B is chiral and A is achiral
C) Both are chiral
D) Both are achiral
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a
38. Consider the cubic and orthorhombic unit cells, with internal angles = 90°, as shown
below. What is the angle between the face diagonals (AF and FC, marked by dashed lines) in
each of the cases?

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a

m
A) Orthorhombic: 29.6°, Cubic: 60°
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B) Orthorhombic: 45°, Cubic: 60° la
a g
C) Orthorhombic: 33.3°, Cubic: 109.5°

D) Orthorhombic: 49.4°, Cubic: 60°

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ag For more Question Papers, Sample Papers, Notes & Syllabus visit Page 39 of 41

39. The plots 1 and 2 represent changes in the concentration of a drug in the plasma as a
function of time. This drug was administered at the same dose to a patient either
intravenously or orally.

Identify which plots correctly represent the two administration modes:

A) Plot-1 is oral and Plot-2 is intravenous
B) Plot-1 is intravenous and Plot-2 is oral
C) Can not be determined as it depends on the nature of the drug molecule
D) Can not be determined as it depends on the dose of the drug administered
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a For more Question Papers, Sample Papers, Notes & Syllabus visit Page 41 of 41