Practice Pakistan's most useful MCQs for competitive exams

A reasonably general expression for vapour-liquid phase equilibrium at low to moderate pressure is φi yi P = Yi xifi° where, Φ is a vapor fugacity component, Yi is the liquid activity coefficient and fi° is the fugacity of the pure component i. the Ki value (Yi = Ki xi) is therefore, in general a function of ______________________?

• (A)  Temperature only
• (B)  Temperature and pressure only
• (C)  Temperature, pressure and liquid composition xi only
• (D)  Temperature, pressure, liquid composition xi and vapour composition yi

Answer

Submitted By :Ali Uppal

Gibbs-Duhem equation relates composition in liquid phase and the _____________ at constant temperature & pressure?

• (A)  Fugacity
• (B)  Partial pressure
• (C)  Activity co-efficient
• (D)  All (A), (B), and (C)

Answer

Submitted By :Ali Uppal

Critical temperature is defined as the temperature above which a gas will____________________?

• (A)  Not liquify (barring exceptions)
• (B)  Immediately liquify
• (C)  Never liquify however high the pressure may be
• (D)  None of these

Answer

Submitted By :Ali Uppal

The expression for entropy change given by, ΔS = nR ln (V2/V1) + nCv ln (T2/T1) is valid for ______________________?

• (A)  Reversible isothermal volume change
• (B)  Heating of a substance
• (C)  Cooling of a substance
• (D)  Simultaneous heating and expansion of an ideal gas

Answer

Submitted By :Ali Uppal

With increase in reduced temperature, the fugacity co-efficient of a gas at constant reduced pressure___________________?

• (A)  Increases
• (B)  Decreases
• (C)  Remain same
• (D)  Decreases linearly

Answer

Submitted By :Ali Uppal

Which of the following is not a reversible process ?

• (A)  Expansion of an ideal gas against constant pressure
• (B)  Atmospheric pressure vaporisation of water at 100°C
• (C)  Solution of NaCl in water at 50°C
• (D)  None of these

Answer

Submitted By :Ali Uppal

Equilibrium constant of a reaction varies with the____________________?

• (A)  Initial concentration of the reactant
• (B)  Pressure
• (C)  Temperature
• (D)  None of these

Answer

Submitted By :Ali Uppal

For a cyclic process, a fixed ratio between heat and work___________________?

• (A)  Always exists
• (B)  May exist
• (C)  Never exists
• (D)  Is difficult to predict

Answer

Submitted By :Ali Uppal

When dilute aqueous solutions of two salts are mixed, the process is associated with ___________________?

• (A)  Decrease in temperature
• (B)  Increase in temperature
• (C)  No change in temperature
• (D)  Change in temperature which is a function of composition

Answer

Submitted By :Ali Uppal

For an incompressible fluid, the _______________ is a function of both pressure as well as temperature?

• (A)  Internal energy
• (B)  Enthalpy
• (C)  Entropy
• (D)  All (A),

Answer

Submitted By :Ali Uppal