List of top Physical Chemistry Questions

The following figure shows an experimental liquid-liquid phase diagram of phenol and water at the vapor pressure of the system. The total amount of phenol and water (in mol) present in the phenol-rich phase when 5 mol of water was shaken with 5 mol of phenol at 40 °C is _______.

(rounded off to one decimal place)

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

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)

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]

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

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]

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

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]

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)

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)

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

0.1 M aqueous solution of a weak monobasic acid has pH 2.0. The pKa of the monobasic acid is _______. (rounded off to one decimal place)

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.]

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 following compound

the number of signals expected in the 1H NMR spectrum is _________.

The stretching frequency of CO in H₃B.CO is

For a zero-order reaction P→Q, the concentration of P becomes half of its initial concentration in 30 minutes after starting the reaction.
The concentration of P becomes zero at ____ minutes. (rounded off to the nearest integer)

The function exp(−2(𝑥-1)²) attains a maximum at 𝑥= _______. (rounded off to the nearest integer)

For one mole of an ideal gas, the correct statement(s) is/are
[𝑈=internal energy; 𝑉= volume; 𝑇=temperature; 𝑃=pressure]

Consider the exothermic chemical reaction O₂(𝑔)+2H₂(𝑔) ⇌ 2H₂O(𝑔) at equilibrium in a closed container. The correct statement(s) is/are

The correct assumption(s) required to derive Langmuir adsorption isotherm is/are

A pair of isosteric compounds is

B₂ and C₂, respectively, are

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