Questions 511–520 of 650. Imported answers require independent review unless marked reviewed.

Topic practice 650 questionsPage 52 of 65

Question 46

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The specific rotation of optically pure (R)-2-bromobutane is −112.00. A given sample of 2-bromobutane exhibited a specific rotation of −82.88. The percentage of (S)-(+)-enantiomer present in this sample is ________.

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Question 47

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Consider the following two parallel irreversible first order reactions at temperature T,
P → Q (k₁) P → R (k₂)
Diagram for Chemistry question 47

where k₁ and k₂ are the rate constants and their values are 5 × 10⁻² and 15 × 10⁻² min⁻¹, respectively, at temperature T. If the initial concentration of the reactant ‘P’ is 4 mol L⁻¹, then the concentration of product ‘R’ after 10 min of reaction is ______ mol L⁻¹. (Round off to two decimal places)
(Assume only P is present at the beginning of the reaction.)

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Question 48

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Consider the following equilibrium

At 298 K, the standard molar Gibbs energies of formation, ΔfG°, of SO₂(g) and SO₃(g) are −300 and −371 kJ mol⁻¹, respectively. The value of the equilibrium constant, Kₚ, at this temperature is ______ × 10¹⁰. (Round off to the nearest integer)
(Gas constant R = 8.31 J mol⁻¹ K⁻¹)

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Question 49

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Consider the electrochemical cell
M(s)|M₂(s)|M₂(aq)|M(s)
where ‘M’ is a metal. At 298 K, the standard reduction potentials are E°M²⁺(aq)/M(s) = −0.12 V, E°M₂(s)/M(s) = 0.36 V and the temperature coefficient is (∂E°cell/∂T)ₚ = 1.5 × 10⁻⁴ V K⁻¹. At this temperature the standard enthalpy change for the overall cell reaction, ΔrH°, is ______ kJ mol⁻¹. (Round off to two decimal places)
(Faraday constant F = 96500 C mol⁻¹)

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Question 50

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The normal boiling point of a compound (X) is 350 K (heat of vaporization, ΔvapH = 30 kJ mol⁻¹). The pressure required to boil ‘X’ at 300 K is ______ Torr. (Round off to two decimal places)
(Ignore the temperature variation of ΔvapH; Gas constant R = 8.31 J mol⁻¹ K⁻¹ and 1 atm = 760 Torr)

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Question 51

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For a bimolecular gas phase reaction P + Q → R, the pre-exponential factor is 1 × 10¹³ dm³ mol⁻¹ s⁻¹. The standard entropy of activation at 25 °C is ______ J K⁻¹ mol⁻¹. (Round off to two decimal points)
(The standard concentration c° = 1 mol dm⁻³, Planck constant h = 6.62 × 10⁻³⁴ J s; Boltzmann constant kB = 1.38 × 10⁻²³ J K⁻¹; Gas constant R = 8.31 J mol⁻¹ K⁻¹)

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Question 52

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Character table of point group D₈ is given below.
D₈
E
2C₈
2C₄
2C₈³
C₂
4C₂′
4C₂″
A₁
a
1
1
1
1
1
1
A₂
b
1
1
1
1
h
i
B₁
c
−1
1
−1
1
1
j
B₂
d
−1
1
−1
1
−1
1
E₁
e
√2
0
−√2
−2
0
0
E₂
f
0
−2
0
k
0
0
E₃
g
−√2
0
√2
−2
0
0
Value of (a + b + c + d + e + f + g + h + i + j + k) is equal to ________

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Question 53

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If

, where

and

are spin angular momentum operators and

is spin up eigen function, then the value of ‘a’ is ________. (Round off to one decimal place)

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Question 54

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A particle in one dimensional box of length

with potential energy

is perturbed by the potential

eV, where

is a constant. The 1st order correction to the 1st excited state of the system is __________ ×

eV.

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Question 55

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Consider a two dimensional harmonic oscillator with angular frequency

. The wavelength of x polarized light required for the excitation of a particle from its ground state to the next allowed excited state is ________ ×

m. (Round off to one decimal place)
(Speed of light

)

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