List of top Physical Chemistry Questions

In thermogravimetric analysis, 12.45 mg of CuSO₄.5H₂O was subjected to heating under N₂ atmosphere. At a particular temperature, there was a weight loss of 3.6 mg. The number of water molecule(s) lost per formula unit is _____.
(Given molar mass (in g mol^-1) of H = 1.0, O = 16.0, S = 32.0, and Cu = 63.5)
(rounded off to the nearest integer)

In the cell reaction
P⁺(𝑎𝑞)+Q(𝑠)→P(𝑠)+Q⁺(𝑎𝑞) 
the EMF of the cell, 𝐸_{𝑐𝑒𝑙𝑙} is zero. The standard EMF of the cell, 𝐸^𝑜_{𝑐𝑒𝑙𝑙} is 
[Given: 
Activities of all solids are unity. 
Activity of P⁺(𝑎𝑞) is 2 M. Activity of Q⁺(𝑎𝑞) is 1 M. 
𝑅 = universal gas constant; 𝑇 = temperature; 𝐹 = Faraday constant]

The partial vapor pressure of 0.1 molal solution of B in liquid A is 60 kPa at 300 K. The partial vapor pressure (in kPa) of a solution containing B with mole fraction of 0.1 in liquid A at 300 K is ______.
(Assume the solute B obeys Henry's law. The molar mass of A is 80 g mol^-1.)
(rounded off to three decimal places)

A system undergoes one clockwise cycle from point X back to point X as shown in the figure below:

The correct statement about this process is

Critical micellar concentration of a surfactant is 0.008 M in water at 25 °C. If the aggregation number of the micelles is 80, the concentration of the micelles (in M) present in 0.088 M aqueous solution of the surfactant at 25 °C is

A salt QCl of a certain metal Q is electrolyzed to its elements. 40 g of metal Q is formed at an electrode. The volume of Cl₂ formed at the other electrode at 1 atm pressure and 298 K is _______ litres. (rounded off to one decimal place)
[Given: The gas constant 𝑅 = 0.082 L atm mol⁻¹ K⁻¹ , the molar mass of Q is 40 g mol⁻¹ and Cl₂ is assumed to be an ideal gas]

The correct statement(s) about ⁴D_5/2 state of an atom is (are) :

The unit cell of a two-dimensional square lattice with lattice parameter a is indicated by the dashed lines as shown below:

The percentage (%) area occupied by the grey circles (of radius r) inside the unit cell is _______. (rounded off to the nearest integer)

2 mol of a monoatomic ideal gas with initial volume of 5 L and pressure 10 bar undergoes an irreversible adiabatic expansion against a constant final pressure of 1 bar. The final volume (in L) is _______.
(Given: R = 8.314 × 10^-2 L bar mol^-1 K^-1)
(rounded off to one decimal place)

The ratio of osmotic pressures of aqueous solutions of 0.01 M BaCl₂ to 0.005 M NaCl is
[Given: Both compounds dissociate completely in water]

In the oxidation of phosphorus with oxygen, 0.2 mol of P₄ produces ____ g of P₄O₁₀.
(rounded off to one decimal place) 
[Given: Atomic weight of P = 31; Atomic weight of O = 16]

An element E has three isotopes:
\(28\\14 E\) (abundance 92.21%, atomic mass: 27.977 a.m.u.), 
\(29\\14 E\) (abundance 4.70%, atomic mass: 28.976 a.m.u.), and 
\(30\\14 E\) (abundance 3.09%, atomic mass: 29.974 a.m.u). 
The atomic mass of E is _______ a.m.u. 
(rounded off to three decimal places

The total vapour pressure of an ideal binary liquid mixture of benzene and toluene is 0.3 bar. The vapour pressure of pure benzene is 0.5 bar and that of toluene is 0.2 bar. The mole fraction of benzene in this mixture is _______.
(rounded off to two decimal places)

The wavelength of the γ-ray emitted in

is _______ Å. (rounded off to three decimal places)
[Given: h=6.626×10 ⁻³⁴ J s; c=2.998×10⁸ m s⁻¹ ; 1 MeV=1.602×10⁻¹³ J]

If 1 M of a dye in water transmits 50% of incident light at 400 nm, then 2 M of the dye in water transmits _______ % of the incident light at 400 nm. (rounded off to the nearest integer)
[Given: Both experiments are performed in the same spectrophotometric cell.]

A 1.0 L solution is prepared by dissolving 2.0 g of benzoic acid and 4.0 g of sodium benzoate in water. The pH of the resulting solution is _______. (rounded off to one decimal place)
Given: Molar mass of benzoic acid is 122 g mol⁻¹ 
Molar mass of sodium benzoate is 144 g mol⁻¹ 
p𝐾_a of benzoic acid is 4.2

Consider the wavefunction 𝜓(𝑥) = 𝑁[exp(𝑖𝑘𝑥) + exp(−𝑖𝑘𝑥)]. The complex conjugate 𝜓 ∗ (𝑥) is [Given: 𝑁 is the normalization constant; 𝑖=\(\sqrt-1\)]

Wavelength of X-rays used in a diffraction experiment is 1.54 Å. X-rays are diffracted from a set of planes with an interplanar spacing of 1.54 Å. Then the angle θ (in degrees) corresponding to the first-order Bragg diffraction is

Consider photoelectric effect. The number of incident photons is the same for all frequencies. The plot that best describes the dependence of the number of photoelectrons (n) emitted as a function of the incident light frequency (ν) is

Identify the reaction for which, at equilibrium, a change in the volume of the closed reaction vessel at a constant temperature will not affect the extent of the reaction

A pair of isosteric compounds is

Mobility of ions Li⁺ , Na⁺ , K⁺ , Ag⁺ in water at 298 K follows the order

The magnitude of energy difference between the energy levels 𝑛=3 and 𝑛=2 of a quantum particle of mass 𝑚 in a box of length L is \(\frac{Xℎ ^2}{ 8𝑚L ^2} .\) 
Then X = _______. 
(rounded off to the nearest integer) 
[Given: ℎ is Planck’s constant and 𝑛 denotes the quantum number]

The enthalpy change for the reaction
C(𝑔) +\( \frac{1}{2}\) O₂(𝑔)→CO(𝑔) is _______ kJ per mole of CO(𝑔) produced. 
(rounded off to one decimal place) 
[Given: 
C(𝑔)+O₂(𝑔) → CO₂(𝑔), ΔH_rxn = −393.5 kJ per mole of CO₂(𝑔) produced 
CO₂(𝑔) → CO(𝑔) +\( \frac{1}{2}\) O₂(𝑔), ΔH_rxn = 283.0 kJ per mole of CO(𝑔) produced]

For the reaction

if the concentration of KCN is increased four times, then the rate of the reaction would be