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Right OPTION is (d) 6.57 × 10^-5 m^3/N

The EXPLANATION: Specific VOLUME = 1/(Specific weight)

= 1/(1.52×104 N/m^3)

= 6.57 × 10^-5 m^3/N.

The correct option is (a) 0.445 kg/m^3

To EXPLAIN I would say: Known: Absolute viscosity μ = 0.89 Ns/m^2, kinematic viscosity ν = 2 m^3/s.

The density is GIVEN by,

\(p=\frac{u}{V}\)

\(p=\frac{0.89 Ns^2}{2 m^2}\)

p = 0.445kg/m^3

Therefore, the density of FLUID is 0.445kg/m^3.

Right CHOICE is (a) Penicillium chrysogenum

The best I can EXPLAIN: Penicillium chrysogenum has a Shear rate (s^-1) of 1-15 and is a Casson plastic and applicable under TURBINE IMPELLER.

Right OPTION is (a) 1.55

The BEST EXPLANATION: Given DATA: Mass density = 1550 kg/m^3

Right option is (b) NEWTONIAN fluid

Explanation: Newtonian fluids undergo strain rates proportional to the applied shear stress. It is defined to be a fluid whose shear stress is LINEARLY proportional to the velocity gradient in the direction PERPENDICULAR to the plane of shear. This DEFINITION means regardless of the forces ACTING on a fluid, it continues to flow.

Right choice is (b) False

The best I can explain: The DENSITY of liquids is PRACTICALLY independent of pressure; liquids are INCOMPRESSIBLE FLUIDS. If the density of a fluid changes with pressure, the fluid is compressible. GASES are generally classed as compressible fluids.

Right choice is (a) Shear FORCES

The EXPLANATION: Shear forces in turbulent eddies stretch and distort the bubbles and break them into smaller sizes; at the same time, SURFACE tension at the gas-liquid interface TENDS to restore the bubbles to their spherical shape. In the case of solid material such as cell flocs or aggregates, shear forces in turbulent flow are resisted by the mechanical STRENGTH of the particles.

Correct answer is (a) True

The explanation: Propellers COMMONLY refer to devices which MOVE an attached object. For example, a SHIP’s propeller moves the ship itself forward or backward. IMPELLERS, on the other hand, are designed to move the substance — fluid or GAS passing through it without moving the object it is attached to.

The CORRECT answer is (B) False

To ELABORATE: Near the impeller there is a region of high turbulence where fluid cur- rents converge and exchange material. Away from the impeller, flow is slower and largely streamline; mixing in these regions is MUCH less INTENSE than near the impeller.

The correct option is (a) 3:1

Best explanation: Mixing is achieved using an impeller mounted in the tank; for use with Newtonian fluids, the ratio of tank DIAMETER to impeller diameter is normally about 3:1. The impeller is usually positioned OVERHEAD on a centrally-located stirrer shaft. For efficient mixing with a SINGLE impeller, the DEPTH of liquid in the tank should be no more than 1.0-1.25 times the tank diameter.

Correct choice is (b) False

For explanation I WOULD say: A fluid’s viscosity strongly depends on its temperature. Along with the shear rate, temperature really is the dominating influence. The higher the temperature is, the lower a SUBSTANCE’s viscosity is. Consequently, decreasing temperature CAUSES an increase in viscosity. The relationship between temperature and viscosity is inversely PROPORTIONAL for all SUBSTANCES. A change in temperature always affects the viscosity – it depends on the substance just how much it is influenced by a temperature change. For some fluids a decrease of 1°C already causes a 10 % increase in viscosity.

The correct choice is (B) 24.1 cP

Easiest EXPLANATION: Rearranging POISEUILLE’s EQUATION we get

Right CHOICE is (d) Xanthomonas campestris

Explanation: Xanthomonas campestris has a Shear rate (s^-1) of 0.0035-100 and is a PSEUDOPLASTIC, K increases continually; N levels off when xanthan CONCENTRATION reaches 0.5%; cell mass (max 0.6%) has relatively little effect on viscosity.

Right choice is (a) Pascal – second

Best explanation: Apparent VISCOSITY has the SI DERIVED UNIT Pa•s (Pascal-second, but the CENTIPOISE is frequently used in practice: (1 mPa•s = 1 cP).

Correct choice is (b) Water

To elaborate: Water is a Newtonian fluid, because it continues to display fluid properties no MATTER how much it is stirred or mixed. A slightly less rigorous definition is that the drag of a small object being moved slowly through the fluid is PROPORTIONAL to the force applied to the object. (Compare friction). Important fluids, like water as WELL as most gases, behave – to good approximation – as a Newtonian fluid under NORMAL conditions on Earth.

Correct choice is (C) 4

To ELABORATE: Degree of AGITATION = bulk fluid velocity / 6

= 23.55/6 = 3.93 ∼ 4

Right choice is (a) Increased osmotic pressure and low turgor pressure

Best explanation: Osmotic pressure of the culture medium affects cell turgor pressure. This in TURN affects the HYPHAL FLEXIBILITY of filamentous cells; increased osmotic pressure gives a lower turgor pressure making the hyphae more flexible. IMPROVED hyphal flexibility reduces BROTH viscosity, and can also have a marked effect on yield stress.

The CORRECT choice is (c) Depends on the shear rate

Explanation: APPARENT VISCOSITY (sometimes denoted η) is the shear stress applied to a FLUID divided by the shear rate. For a Newtonian fluid, the apparent viscosity is constant, and equal to the Newtonian viscosity of the fluid, but for non-Newtonian fluids, the apparent viscosity depends on the shear rate. In such case, the ratio between shear stress and shear rate is not constant; NEVERTHELESS, this ratio for non- Newtonian fluids.

Right answer is (c) 100 kPascal

Easiest explanation: A bar (b) is a metric measurement unit of PRESSURE. One bar is equivalent to ten NEWTONS (N) PER square centimeter (cm^2).

1 bar = 100,000 Pascal = 100,000 N/m^2 = 100,000 N / (100*100cm^2) = 10 N/cm^2.

The correct choice is (b) BERNOULLI’s equation

Explanation: The flow speed of a fluid can be measured using a device such as a Venturi meter or an orifice plate, which can be placed into a pipeline to reduce the diameter of the flow. For a horizontal device, the CONTINUITY equation shows that for an incompressible fluid, the reduction in diameter will cause an increase in the fluid flow speed. SUBSEQUENTLY, Bernoulli’s principle then shows that there must be a DECREASE in the pressure in the reduced diameter region. This phenomenon is known as the Venturi EFFECT.

The correct choice is (c) 0.835

The best EXPLANATION: GIVEN Data: VELOCITY PROFILE v = 5y^2 + y;

μ = 8.35 poise

Substituting y=0 on the above equation, we get shear stress at RESPECTIVE depths.

τ = 0.835

Correct ANSWER is (b) Rushton turbine

To elaborate: The Rushton turbine is a radial flow impeller used for many mixing applications (commonly for gas dispersion applications). The design is based on a flat disk with vertical flat BLADES VERTICALLY MOUNTED.

Right CHOICE is (d) 0.052 m^2 s^-3

Explanation: \(\lambda^4 = \FRAC{v^3}{\varepsilon}\)

\(\varepsilon = \frac{v^3}{λ^4}\)

Therefore,

\(\varepsilon = \frac{(1.29×10^{-6})^3 \,m^6 \,s^{-3}}{(8×10^{-5})^4 m^4}\) = 0.052 m^2 s^-3.

Right choice is (a) Distribution

The explanation is: Distribution is an IMPORTANT process in MIXING, but can be RELATIVELY slow. In LARGE tanks, the size of the circulation paths is also large and the time taken to traverse them is long; this, together with the REGULARITY of fluid pumping at the impeller, inhibits rapid mixing. Accordingly, distribution is often the slowest step in the mixing process.

The correct answer is (C) 1/10-1/12

To explain: The optimum BAFFLE width depends on the IMPELLER design and FLUID viscosity but is of the order 1/10-1/12 the tank diameter.

Right option is (a) Color

To explain I WOULD say: Five primary factors determine blood viscosity. These include hematocrit, erythrocyte deformability, plasma viscosity, erythrocyte aggregation, and temperature. Hematocrit is the most obvious determinant of WBV. A higher PERCENTAGE of RED blood CELLS (RBCs) results in thicker blood.

The correct CHOICE is (B) 9 kN/m^3

For explanation I would say: Given DATA: VOLUME = 5 m^3

Weight = 45 kN

Right option is (c) Poise

The BEST I can EXPLAIN: The unit of VISCOSITY (.in C.G.S) is poise.

One poise = 0.1 N.s / m^2,

µwater = 10^-3 NS / m^2

µair = 1.81 X 10^-5 Ns / m^2.

Correct choice is (d) TOOTHPASTE

Easiest explanation: A Bingham plastic is a viscoplastic material that behaves as a rigid body at low stresses but flows as a viscous FLUID at high stress. It is used as a common mathematical model of mud flow in drilling engineering, and in the handling of SLURRIES. A common example is toothpaste, which will not be EXTRUDED until a certain pressure is applied to the tube. It then is PUSHED out as a solid plug.