What does the selectivity parameter in a competing reaction system measure?

The correct answer is B: The ratio of desired product to undesired product formation rates. Selectivity S = rate of desired product formation / rate of undesired product formation, used to optimize reactor conditions for maximum desired product yield

A first-order reaction has a rate constant of 0.693 min⁻¹. What is its half-life?

The correct answer is A: 1 minute. For first-order reactions, t₁/₂ = 0.693/k = 0.693/0.693 = 1 minute

The Moody diagram is used to determine friction factor for pipe flow. It shows that friction factor increases with:

The correct answer is B: Increasing relative roughness and decreasing Reynolds number. In the Moody diagram, friction factor decreases with increasing Re in laminar region. In turbulent region, f increases with relative roughness (ε/D) and slightly decreases with increasing Re for rough pipes.

A CSTR operating at steady state processes an exothermic reaction. If the inlet temperature increases by 10°C while maintaining constant coolant flow rate, which parameter is most likely to increase?

The correct answer is B: Conversion. Higher inlet temperature increases reaction rate (via Arrhenius equation) in an exothermic reaction, leading to higher conversion. Heat removal capacity depends on coolant flow and ΔT.

In a distillation column, the interface equilibrium at the liquid-vapor boundary can be described by:

The correct answer is C: Either Raoult's Law or Henry's Law depending on the system. Raoult's Law applies to ideal solutions (high concentration), while Henry's Law applies to dilute solutions. The choice depends on the system behavior.

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133 Q 5 Topics Take Mock Test

Difficulty: All Easy Medium Hard 71–80 of 133

Topics in Chemical Engineering

All Mass Transfer 100 Heat Transfer 100 Fluid Mechanics 100 Chemical Reaction Engineering 100 Thermodynamics 97

Q.71 Easy Fluid Mechanics

A centrifugal pump operates with water (ρ = 1000 kg/m³) at an impeller diameter of 0.3 m and rotational speed of 1500 RPM. Calculate the peripheral velocity at the impeller tip.

A 23.56 m/s

B 15.71 m/s

C 31.42 m/s

D 47.12 m/s

Correct Answer: A. 23.56 m/s

EXPLANATION

Peripheral velocity = π × D × N / 60 = π × 0.3 × 1500 / 60 = 23.56 m/s

Test

Q.72 Easy Fluid Mechanics

The relative roughness of a pipe is defined as:

A Absolute roughness height only

B Ratio of absolute roughness to pipe diameter

C Product of roughness and pipe length

D Roughness divided by fluid viscosity

Correct Answer: B. Ratio of absolute roughness to pipe diameter

EXPLANATION

Relative roughness ε/D = (absolute roughness)/(pipe diameter). This dimensionless parameter determines flow behavior in the Moody chart for turbulent flow calculations.

Test

Q.73 Easy Fluid Mechanics

In a U-tube manometer measuring differential pressure, if one side contains mercury (ρ = 13600 kg/m³) with a height difference of 250 mm, what is the differential pressure?

A 32.4 kPa

B 33.3 kPa

C 34.2 kPa

D 35.1 kPa

Correct Answer: B. 33.3 kPa

EXPLANATION

ΔP = ρ_mercury × g × h = 13600 × 9.81 × 0.25 = 33,324 Pa ≈ 33.3 kPa

Test

Q.74 Easy Fluid Mechanics

Which of the following pump types operates on the principle of positive displacement with rotating screws?

A Centrifugal pump

B Reciprocating pump

C Screw pump

D Jet pump

Correct Answer: C. Screw pump

EXPLANATION

Screw pumps (Archimedean screw or progressive cavity pumps) use rotating screws for positive displacement. They are used for high viscosity fluids.

Test

Q.75 Easy Fluid Mechanics

Which dimensionless number is used to characterize the ratio of inertial forces to viscous forces in fluid flow?

A Froude number

B Reynolds number

C Mach number

D Strouhal number

Correct Answer: B. Reynolds number

EXPLANATION

Reynolds number (Re = ρVD/μ) represents the ratio of inertial to viscous forces and determines the flow regime (laminar, transitional, or turbulent).

Test

Q.76 Easy Fluid Mechanics

For laminar flow of a viscous fluid between two parallel plates, the velocity profile is:

A Linear

B Parabolic

C Logarithmic

D Exponential

Correct Answer: B. Parabolic

EXPLANATION

For laminar flow between parallel plates (Poiseuille flow), the velocity profile is parabolic due to the balance between pressure gradient and viscous forces.

Test

Q.77 Easy Fluid Mechanics

A fluid with dynamic viscosity of 0.8 Pa·s and density of 900 kg/m³ flows through a circular pipe. What is the kinematic viscosity of this fluid?

A 8.89 × 10⁻⁴ m²/s

B 1.12 × 10⁻³ m²/s

C 720 m²/s

D 1.125 × 10⁻³ m²/s

Correct Answer: A. 8.89 × 10⁻⁴ m²/s

EXPLANATION

Kinematic viscosity ν = μ/ρ = 0.8/900 = 8.89 × 10⁻⁴ m²/s

Test

Q.78 Easy Fluid Mechanics

Which pumping principle is used in a gear pump?

A Dynamic principle (Bernoulli effect)

B Positive displacement principle

C Gravity principle

D Capillary action

Correct Answer: B. Positive displacement principle

EXPLANATION

Gear pumps are positive displacement pumps. They move fixed volumes of fluid per rotation. Dynamic principle applies to centrifugal pumps.

Test

Q.79 Easy Fluid Mechanics

In fluid mechanics, which dimensionless number represents the ratio of inertial forces to viscous forces?

A Reynolds number

B Froude number

C Weber number

D Mach number

Correct Answer: A. Reynolds number

EXPLANATION

Reynolds number Re = (Inertial forces)/(Viscous forces) = ρVD/μ. It characterizes flow regime (laminar vs turbulent).

Test

Q.80 Easy Fluid Mechanics

For a Newtonian fluid, shear stress (τ) is related to shear rate (dV/dy) by:

A τ = μ(dV/dy)

B τ = k(dV/dy)ⁿ

C τ = μ₀ + k(dV/dy)ⁿ

D τ proportional to (dV/dy)²

Correct Answer: A. τ = μ(dV/dy)

EXPLANATION

Newton's law of viscosity: τ = μ(dV/dy). Option B is power law (non-Newtonian), C is Bingham plastic model.

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