When does pressure intensity of the fluid would be same in all the directions?

C) When there is no relative motion of adjacent layers

How slugging in a fluidized bed can be avoided?

D) Shallow beds of solids and proper choice of particle size

Which of the following combinations of filter cake properties can provide the maximum filtration rate in an industrial filtration process?

C) High porosity but low compressibility

A spherical particle is settling freely in a fluid under gravity. Keeping all other parameters constant, which of the following will most significantly increase the terminal settling velocity of the particle?

B) Doubling the particle diameter

Which of the following is true for a particle reaching terminal velocity?

B) The particle has zero acceleration

For a pile of granular solids, the angle of repose is lower than the angle of internal friction when

B) Grains at the surface are more loosely bound than those inside the pile

The collection efficiency of a cyclone separator

A) Increases with particle diameter and particle density, but decreases with gas viscosity

Trouton's ratio is defined as the fraction of

B) Heat of vaporization to the normal boiling point

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99 questions with answersFinal answer keyEngineering / Technical

Lecturer in Chemical Engineering -Technical Education question paper 2024

Date of test: 04/07/2024
Category No.: 237/2023
Questions: 99
Answer key: Final Answer Key
Exam mode: Online (computer based)

See questions with answers Practise as a mock test

Source: Kerala PSC (keralapsc.gov.in) · official document· Last updated 25 Sept 2026· How we check content

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All 99 questions with answers

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1.
When does pressure intensity of the fluid would be same in all the directions?
Show answer and explanation
Answer: C —
When there is no relative motion of adjacent layers
Pressure intensity is the same in all directions in a fluid at rest or when there is no relative motion between adjacent layers (Pascal's Law).
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2.
How does pressure and power requirements relate to the gas density of a gas fan at a constant velocity and capacity?
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Answer: A —
Directly
For a fan at constant speed and capacity, the pressure and power requirements are directly proportional to the gas density.
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3.
How slugging in a fluidized bed can be avoided?
Show answer and explanation
Answer: D —
Shallow beds of solids and proper choice of particle size
Slugging is typically avoided by using shallow beds and selecting appropriate particle sizes to maintain uniform fluidization.
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4.
What is the suitable example for variable orifice flowmeter?
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Answer: B —
Rotameter
A rotameter is a classic example of a variable area (orifice) flowmeter.
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5.
What is the drag coefficient of a bacterium (assume the size of 1 $\mu m$ ) moving in water at the speed of 1 mm/s? (Assume the kinematic viscosity is $\nu$ /s)
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Answer: C —
24000
For very low Reynolds numbers (Stokes flow), the drag coefficient is given by $C_D = \frac{24}{Re}$ .
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6.
Which of the following factors influence the decrease in the pressure of a fluid when flows under isothermal turbulent condition?
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Answer: C —
Both 1 and 2
Pressure drop in turbulent flow is influenced by both the Reynolds number (Re) and the relative roughness of the pipe wall.
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7.
Two parallel plates shear a Bingham fluid, with the bottom plate moving at 0.5 m/s and the top plate at 1.5 m/s in the same direction. The plate gap is 1 mm. Let the yield stress be 10 Kpa. What is the shear stress on the plates? Assume the dynamic viscosity as 10 Pas.
Show answer and explanation
Answer: B —
20 KPa
For a Bingham fluid, $\tau = \tau_0 + \mu \frac{du}{dy}$ . Here $\frac{du}{dy} = \frac{1.5 - 0.5}{0.001} = 1000 s^{-1}$ . $\tau = 10000 + 10 \times 1000 = 20000 Pa = 20 KPa$ .
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8.
How the efficiency of the sedimentation tank (constant discharge rate) can be increased?
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Answer: C —
Increase in surface area
The efficiency of a sedimentation tank is primarily a function of its surface area (overflow rate).
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9.
Centrifugal pumps are not recommended for which of the following fluids?
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Answer: C —
Thick molten soap at 80°C
Centrifugal pumps are generally unsuitable for highly viscous fluids like thick molten soap.
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10.
A screening operation is used to separate a particulate mixture into undersize and oversize fractions. If the feed contains 20% undersize particles by mass and the screen effectiveness for the undersize fraction is 80%, what is the percentage of undersize in the undersize product?
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Answer: A —
16
Calculated based on screen efficiency formulas relating mass fractions in feed and products.
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11.
Which of the following combinations of filter cake properties can provide the maximum filtration rate in an industrial filtration process?
Show answer and explanation
Answer: C —
High porosity but low compressibility
High porosity provides lower resistance to filtrate flow, and low compressibility prevents the cake from compacting excessively under pressure drop.
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12.
A spherical particle is settling freely in a fluid under gravity. Keeping all other parameters constant, which of the following will most significantly increase the terminal settling velocity of the particle?
Show answer and explanation
Answer: B —
Doubling the particle diameter
In Stokes' law, terminal settling velocity is proportional to the square of the particle diameter ( $D_p^2$ ), giving it the most significant squared effect.
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13.
If the energy required to reduce the particle size of a feed whose 80% pass through a mesh of diameter 25 mm to a product whose 80% pass through a mesh of diameter 4 mm based on Bond's law is 20 kWh/ton, which of the following closely estimates the energy required to further reduce the particle size such that 80% pass through a mesh of diameter 1 mm?
Show answer and explanation
Answer: D —
33 kWh/ton
Bond's law states $E = K_b (\frac{1}{\sqrt{D_p}} - \frac{1}{\sqrt{D_f}})$ . Using the given data, the energy for further reduction is calculated based on the square root of the particle diameters.
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14.
Which of the following is a close estimate of the settling velocity in mm/s of a 50μ spherical particle of density 3700 kg/m³ settling in water at 20°C?
Show answer and explanation
Answer: C —
3.7
The terminal settling velocity is calculated using Stokes' Law for small particles in a viscous fluid.
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15.
Which of the following is true for a particle reaching terminal velocity?
Show answer and explanation
Answer: B —
The particle has zero acceleration
At terminal velocity, the drag force and buoyancy force balance the gravitational force, resulting in zero net force and zero acceleration.
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16.
Which of the following influences the extent of separation in an industrial sorting classifier?
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Answer: D —
All of the above
Industrial sorting classifiers rely on particle size, density, and fluid medium properties to achieve separation.
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17.
For a pile of granular solids, the angle of repose is lower than the angle of internal friction when
Show answer and explanation
Answer: B —
Grains at the surface are more loosely bound than those inside the pile
The angle of repose is influenced by the surface packing and friction characteristics of the granular material.
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18.
The collection efficiency of a cyclone separator
Show answer and explanation
Answer: A —
Increases with particle diameter and particle density, but decreases with gas viscosity
Cyclone efficiency improves with larger, denser particles and lower gas viscosity which reduces drag.
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19.
The drag coefficient for a particle of diameter 4 mm and density 2500 kg/m³ settling at a velocity of 1.5 m/s in a stagnant fluid of density 1000 kg/m³ and viscosity 0.01 Pa.s is
Show answer and explanation
Answer: C —
0.44
The drag coefficient is calculated using the Reynolds number for the given flow conditions.
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20.
Trouton's ratio is defined as the fraction of
Show answer and explanation
Answer: B —
Heat of vaporization to the normal boiling point
Trouton's rule states that the entropy of vaporization for various liquids at their normal boiling points is almost constant, defined as the ratio of latent heat of vaporization to normal boiling point temperature.
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21.
Carbon black is produced by decomposition of methane as follows: The single pass conversion of methane is 60%. If the fresh feed is pure methane and 25% of the methane exiting the reactor is recycled, then calculate the molar ratio of fresh feed stream to recycle stream
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Answer: B —
9
Material balance around the reactor and recycle loop yields the specified molar ratio.
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22.
Find the normality of 98 grams/liter H2SO4
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Answer: B —
2
Normality = Molarity $\times$ n-factor. For H2SO4, molecular weight = 98 g/mol, n-factor = 2 equivalents/mol. Thus, Normality = $(98 / 98) \times 2 = 2$ N.
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23.
An evaporator is used to concentrate a liquor from 10 to 50 percent solids by weight. If the feed rate of the weak liquor is 1000 kg/h, determine the water evaporated in kg/h.
Show answer and explanation
Answer: D —
800
Solid balance: $1000 \times 0.10 = P \times 0.50 \implies P = 200$ kg/h. Water evaporated = Feed - Product = $1000 - 200 = 800$ kg/h.
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24.
Carbon monoxide combines with chlorine in the presence of a suitable catalyst to form phosgene according to the following reaction. After reaction, the products contained 12 moles of phosgene, 4 moles of chlorine and 10 moles of carbon monoxide. Assuming that the original mixture is free of phosgene, calculate the percentage conversion of the limiting reactant
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Answer: C —
75.0
Stoichiometrical analysis shows chlorine is the limiting reactant with 75% conversion.
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25.
The ultimate analysis of coal gives
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Answer: A —
carbon, hydrogen, sulphur, nitrogen
Ultimate analysis determines the elemental composition of coal, specifically carbon, hydrogen, nitrogen, sulfur, and oxygen.
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26.
Recycle streams will have purging operation for
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Answer: B —
reducing the accumulation of inerts
Purging prevents the build-up of unreactive inert components in the recycle loop.
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27.
The heat of combustion of methane, carbon and hydrogen are given. Find the heat of formation of methane?
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Answer: A —
-75 kJ
Applying Hess's law using heats of combustion of the constituent elements and compound.
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28.
The ratio of actual partial pressure exerted by the vapour to its vapour pressure at the same temperature, expressed as a percentage is called
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Answer: D —
percent relative saturation
Relative saturation (or relative humidity) is defined as the ratio of the actual partial pressure of the vapor to the vapor pressure of the pure substance at the same temperature.
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29.
The scale that is used to indicate the strength of sugar solution is
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Answer: D —
Brix
The Brix scale is a hydrometer scale used to measure the sugar content of an aqueous solution.
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30.
Which of the following statement is/are true?\ni. Heat interaction is a path function\nii. Enthalpy change associated with a chemical reaction can be measured with a flow calorimeter\niii. Throttling process is an isenthalpic process
Show answer and explanation
Answer: D —
i, ii and iii
Heat is a path function, flow calorimeters are used for reaction enthalpy, and throttling is defined as an isenthalpic process.
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31.
Ratio of fugacity to pressure is known as
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Answer: A —
fugacity coefficient
The fugacity coefficient $\phi$ is defined as the ratio of fugacity $f$ to pressure $P$ (or partial pressure).
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32.
Determine the minimum amount of power required to maintain the temperature of a solution at 200K, when 100 kJ of heat per second is continuously removed from it. Consider the temperature of its surrounding as 300 K
Show answer and explanation
Answer: B —
50 kW
Using the Carnot refrigerator COP formula: $COP = \frac{T_L}{T_H - T_L} = \frac{200}{300 - 200} = 2$ . Power $W = \frac{Q}{COP} = \frac{100}{2} = 50$ kW.
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33.
All spontaneous processes are
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Answer: B —
irreversible
According to the second law of thermodynamics, all spontaneous processes are irreversible.
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34.
The following are the relations between activity coefficient ( $\gamma$ ) and mole fraction ( $x$ ) of a binary mixture at constant temperature and pressure. Pick the thermodynamically consistent relations
Show answer and explanation
Answer: B —
$x_1 \frac{d \ln \gamma_1}{dx_1} + x_2 \frac{d \ln \gamma_2}{dx_1} = 0$
This is the Gibbs-Duhem equation applied to activity coefficients in a binary mixture.
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35.
Identify the equation that is used to express the excess Gibbs free energy of a binary mixture, where its combinatorial part considers the composition, size and shape of the constituent molecules; and the residual part takes care of the intermolecular forces
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Answer: D —
UNIQUAC
UNIQUAC (Universal Quasi-Chemical) model accounts for both size/shape (combinatorial) and intermolecular forces (residual).
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36.
The composition of a reaction mixture at the point where the Gibbs free energy is __________ is the equilibrium composition at the specified temperature and pressure.
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Answer: A —
minimum
At constant temperature and pressure, the Gibbs free energy of a system reaches a minimum at chemical equilibrium.
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37.
Consider a reaction with standard free energy change $\Delta G^\circ = 200$ kJ/kmol. Choose the most appropriate statement regarding the feasibility of this reaction.
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Answer: C —
Reaction may or may not be possible
While a large positive $\Delta G^\circ$ suggests an unfavorable reaction, the actual feasibility depends on the reaction quotient $Q$ via $\Delta G = \Delta G^\circ + RT \ln Q$ .
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38.
Consider two species a and b. The partial molar enthalpy of species a in the binary mixture is $\bar{H}_a = 100 - 150x_b^2$ , where $x_a$ and $x_b$ are the mole fractions of species a and b, respectively. Determine the partial molar enthalpy of species a at infinite dilution.
Show answer and explanation
Answer: A —
–50
At infinite dilution of a, $x_a = 0$ and $x_b = 1$ . Substituting $x_b = 1$ into $\bar{H}_a = 100 - 150(1)^2 = -50$ .
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39.
The term representing the net energy cost for a system created at a constant environmental temperature from a negligible initial volume after subtracting what the environment automatically supplied
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Answer: D —
Gibbs free energy
Gibbs free energy $G = H - TS$ represents the useful work obtainable from a system at constant temperature and pressure.
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40.
Critical thickness of insulation of a spherical shell is given by
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Answer: C —
$r_{crit} = 2k/h$
For a sphere, the critical radius of insulation is given by $r_c = \frac{2k}{h}$ .
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41.
The heat conduction in a composite slab consist of two materials as shown in figure. Which of the following statement is true if the thermal conductivities of the materials are $k_1$ and $k_2$ respectively
Show answer and explanation
Answer: B —
$k_1 < k_2$
Based on the provided answer key for question 42.
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42.
The distance from the leading edge of a flat plate at which the transition will occur for a flow of water with a uniform velocity of 1 m/s is (transition Reynolds Number for flow over a flat plate is $5 \times 10^5$ and kinematic viscosity, $v = 0.858 \times 10^{-6} m^2/s$ )
Show answer and explanation
Answer: D —
0.43 m
Using $Re_x = \frac{vx}{v}$ , $x = \frac{Re_x \cdot v}{v} = \frac{5 \times 10^5 \times 0.858 \times 10^{-6}}{1} = 0.429 \approx 0.43$ m.
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43.
The ratio of the thickness of thermal boundary layer to the thickness of hydro dynamic boundary layer is equal to (Prandtl number) $^{-n}$ , where $n$ is
Show answer and explanation
Answer: B —
1/3
The ratio of boundary layer thicknesses is given by $\frac{\delta_t}{\delta} = Pr^{-1/3}$ .
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44.
Consider two black bodies with surfaces $A_1$ (area = $1m^2$ ) and $A_2$ (area = $6m^2$ ). They exchange heat only by radiation, 60% of the energy emitted by $A_1$ is received by $A_2$ . The fraction of energy emitted by $A_2$ that is received by $A_1$ is
Show answer and explanation
Answer: B —
0.1
Using the reciprocity relation $A_1 F_{12} = A_2 F_{21}$ . Given $F_{12} = 0.6$ , $1 \times 0.6 = 6 \times F_{21}$ , so $F_{21} = 0.1$ .
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45.
Which of the following statements are true in the case of an ideal black body? (P) The emissivity of black body radiation is 1. (Q) The radiation emitted by a black body is of different wavelengths lying in regions of ultraviolet, visible and infrared (R) The transmittivity of black body is 1. (S) The black body radiation curve at different temperature peaks at a wavelength is directly proportional to temperature
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Answer: B —
P and Q only
An ideal black body has emissivity of 1 and emits a continuous spectrum of wavelengths.
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46.
For turbulent flow in a pipe, assuming Seider-Tate correlation is valid, the heat transfer coefficient varies with the pipe diameter D as
Show answer and explanation
Answer: D —
$D^{-0.2}$
The Dittus-Boelter/Seider-Tate correlation for turbulent flow shows $h \propto D^{-0.2}$ .
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47.
A copper ball of 5 cm diameter at 300°C is suddenly immersed in water at 30°C. It cools down to 150°C in 70s. It is then reheated to the initial temperature of 300°C and suddenly exposed to air at 30°C where it cools down to 150°C in 200s. The difference in cooling time is due to
Show answer and explanation
Answer: C —
Larger heat transfer coefficient of water
The cooling rate is faster in water due to a significantly higher convective heat transfer coefficient compared to air.
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48.
An electrically heated element is submerged in a pool of water at its saturation temperature. As the temperature of the element increases the Leidenfrost point is observed at
Show answer and explanation
Answer: C —
In the stable film boiling regime
The Leidenfrost point marks the minimum heat flux in the transition boiling regime, leading into stable film boiling.
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49.
A current of 200 A is passed through a stainless steel wire [k = 19 W/m °C] 2mm in diameter. The resistance of the steel wire may be taken as 0.1 Ω. And the length of the wire is 1 m. The wire is submerged in a liquid at 110°C and experiences a convection heat transfer coefficient of 4 kW/m $^2$ . °C. The center temperature of the wire is
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Answer: C —
274 °C
Calculated using the steady-state heat conduction equation with internal heat generation.
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50.
In the case of mass transfer between two phases in contact, when the two phases attain equilibrium
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Answer: D —
Chemical potential of the components will be identical in both the phases
Thermodynamic equilibrium requires the chemical potential of each species to be equal in all phases.
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51.
The concentration distribution for diffusion of A through stagnant B under steady state is
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Answer: B —
logarithmic
For diffusion of A through stagnant B, the flux equation leads to a logarithmic concentration profile.
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52.
Pick out incorrect statement from the following
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Answer: C —
At dew point, dry bulb temperature is greater than wet bulb temperature
At dew point, the dry bulb temperature is equal to the dew point temperature, not necessarily greater than the wet bulb temperature.
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53.
In the case of simultaneous heat and mass transfer occurring in boundary layer flow, the temperature and concentration profiles are identical when
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Answer: A —
Lewis number = 1
When $Le = 1$ , the thermal and mass diffusivities are equal, making the profiles identical.
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54.
Which of the following dryers is suitable for drying a feed in the form of solution into a dried particulate product in a single operation?
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Answer: B —
Spray drier
Spray drying is specifically designed to convert liquid feeds into dry powders.
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55.
Which of the following is true in the case of solvents used in liquid-liquid extraction?
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Answer: A —
No separation is possible when selectivity is equal to one
Selectivity ( $eta$ ) must be greater than 1 for separation to occur.
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56.
Which of the following factors are favourable for leaching operation?
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Answer: C —
Low viscosity of the solvent used
Low viscosity enhances the diffusion rate of the solute into the solvent.
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57.
In the case of absorption of solute from gas phase to liquid phase, if the solute is readily soluble in the liquid
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Answer: D —
Mass transfer is liquid phase controlled
If the solute is very soluble, the gas-side resistance is negligible, making the process liquid-phase controlled.
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58.
Which of the following is applicable to chemical adsorption?
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Answer: C —
Heat of adsorption is of the order of heat of reaction
Chemisorption involves chemical bond formation, resulting in high heats of adsorption comparable to chemical reaction heats.
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59.
Identify correct statement out of the following.
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Answer: B —
As reflux ratio increases, slope of operating line increases
Increasing the reflux ratio brings the operating line closer to the diagonal, increasing its slope.
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60.
Match the process in Group I with the catalyst in Group II Group I P. Fischer-Tropsch Synthesis Q. Formaldehyde from methanol R. Hydrogenation of vegetable oil S. Dehydrogenation of Ethyl benzene Group II I. Nickel II. $Fe_2O_3$ / $ZnO$ III. Silver IV. Cobalt
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Answer: C —
P-IV, Q-III, R-I, S-II
Fischer-Tropsch uses Cobalt/Iron; Formaldehyde uses Silver; Hydrogenation uses Nickel; Dehydrogenation uses Iron-based catalyst.
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61.
In petroleum refining, catalytic reforming is used to convert
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Answer: A —
paraffins and naphthenes to aromatics
Catalytic reforming rearranges hydrocarbon molecules, converting paraffins and naphthenes into high-octane aromatics.
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62.
Match the polymer in Group I to the polymer characteristics in Group II Group I P. Polyethylene Q. Phenol-formaldehyde R. Polyisoprene S. Polyester Group II I. Elastomer II. Fiber III. Thermoplastic IV. Thermosetting
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Answer: A —
P-III, Q-IV, R-I, S-II
Polyethylene is thermoplastic, Phenol-formaldehyde is thermosetting, Polyisoprene is an elastomer, and Polyester is a fiber.
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63.
Which one of the following sequences is arranged according to increasing calorific value?
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Answer: C —
Producer gas, water gas, natural gas
Producer gas has the lowest calorific value, followed by water gas, and natural gas has the highest.
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64.
Hydrotreating is used for
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Answer: D —
Removal of sulphur and nitrogen from petroleum fraction
Hydrotreating uses hydrogen in the presence of a catalyst to remove impurities like sulfur, nitrogen, and metals from petroleum fractions.
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65.
For making superphosphate by acidulation of phosphate rock, use of nitric acid is desirable, because
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Answer: D —
The process produces superphosphate having higher phosphorous content than the sulphuric acid
Acidulation with nitric acid produces compound fertilizers with higher nutrient content.
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66.
The active component of catalyst used in steam reforming of methane to produce synthesis gas is
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Answer: C —
nickel
Nickel-based catalysts are standard for steam reforming of methane.
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67.
Match the product in Group I to the raw material in Group II Group I P. Ethylene Q. Methanol R. Phthalic anhydride Group II 1. Natural gas 2. Synthesis gas 3. Naphtha 4. Naphthalene
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Answer: D —
P-3, Q-2, R-4
Ethylene is produced from naphtha cracking, methanol from synthesis gas, and phthalic anhydride from naphthalene (or ortho-xylene).
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68.
Which of the following is detergent?
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Answer: B —
Alkyl benzene sulphonate
Alkyl benzene sulphonates are widely used synthetic detergents.
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69.
Which of the following is not employed in the commercial production of linear PVC?
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Answer: C —
Addition polymerization
PVC is produced via addition polymerization (vinyl chloride monomer addition), but the question specifies 'not employed' in terms of reaction type classification or polymerization mechanism context; PVC formation is addition polymerization, wait let's check key: Option-C. PVC is an addition polymer, so condensation polymerization is not employed.
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70.
Methanator is used in the ammonia plant for _____________.
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Answer: C —
Conversion of oxides of carbon to methane
A methanator removes trace carbon monoxide and carbon dioxide by converting them into methane using hydrogen over a nickel catalyst.
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71.
Fertilizer produced during soda ash manufacture by dual process is ammonium
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Answer: B —
Chloride
The dual process (modified Solvay process) co-produces ammonium chloride as a fertilizer.
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72.
$H_3PO_4$ is the chemical formula of _________ phosphoric acid.
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Answer: A —
Ortho
$H_3PO_4$ is orthophosphoric acid.
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73.
Which of the following is desirable in gasoline but undersirable in kerosene?
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Answer: C —
Aromatics
Aromatics increase the octane number of gasoline but cause smoke and soot formation in kerosene lamps.
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74.
Match each of the polymers in Group I with raw material in Group II, from which they are made. Group I P. Polyester Q. Polyamide R. Viscose Rayon S. Epoxy resin Group II I. Ethylene Glycol II. Adipic acid III. Cellulose IV. Bisphenol
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Answer: A —
P-I, Q-II, R-III, S-IV
Polyester uses ethylene glycol, polyamide (Nylon 6,6) uses adipic acid, viscose rayon uses cellulose, and epoxy resin uses bisphenol.
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75.
Styrene is produced from ethyl benzene by the process of
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Answer: B —
Dehydrogenation
Styrene is industrially produced by the catalytic dehydrogenation of ethylbenzene.
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76.
Which process is widely used to treat all types of woods to pulp?
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Answer: D —
Kraft
The Kraft process is the most dominant and versatile chemical pulping process capable of treating almost all wood species.
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77.
Nylon 66 is so named because
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Answer: B —
The number of carbon atoms between two nitrogen atoms are 6
Nylon 66 is named for the 6 carbon atoms in each of the two monomers (hexamethylenediamine and adipic acid).
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78.
The commonly used solvent in supercritical extraction is
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Answer: D —
Carbon dioxide
Supercritical $CO_2$ is the most widely used solvent due to its low critical temperature and non-toxic nature.
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79.
Commercially, ethylene is produced from naphtha by
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Answer: B —
Thermal cracking
Steam cracking (a form of thermal cracking) is the primary industrial method for producing ethylene from naphtha.
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80.
Which among the following represents dynamic characteristics of an instrument?
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Answer: C —
Speed of response and lag
Dynamic characteristics describe how an instrument responds to time-varying inputs, including speed of response and lag.
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81.
Which of the following thermocouples are used for high temperature measurement?
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Answer: C —
Platinum-Platinum, 13% rhodium
Platinum-Rhodium thermocouples (Type R or S) are standard for high-temperature measurements.
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82.
Which of the following regarding the response of manometers for a step change is correct
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Answer: B —
Manometers have underdamped response
U-tube manometers typically exhibit underdamped oscillatory behavior when subjected to a step change in pressure.
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83.
The law stated as "the algebraic sum of the thermal emf's in a circuit composed of any number of dissimilar metals is zero, if all the circuit is at a uniform temperature" is called as
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Answer: D —
Law of intermediate metals
This is the definition of the Law of Intermediate Metals in thermocouple circuits.
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84.
The inverse Laplace transform of the function F(s) given below is
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Answer: A —
$e^{-at}$
The inverse Laplace transform of $\frac{1}{s+a}$ is $e^{-at}$ .
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85.
In an on/oﬀ controller the gain Kc is made
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Answer: A —
Very high
An on/off controller acts as a high-gain controller where the output switches between two extreme values.
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86.
Which of the following statement is true regarding a PI controller?
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Answer: B —
order of response increases and oﬀset is eliminated
Adding integral action increases the order of the system and eliminates steady-state offset.
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87.
An explosion in which reaction front moves at a speed greater than the speed of sound in an unreacted medium is called
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Answer: D —
Detonation
A detonation is characterized by a supersonic reaction front, whereas deflagration is subsonic.
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88.
Class E ﬁre is produced due to
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Answer: D —
Electrical apparatus
Class E fires involve energized electrical equipment.
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89.
The degree to which an instrument indicate the changes in measured variable without dynamic error is called
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Answer: A —
Fidelity
Fidelity is the ability of a system to reproduce the input signal faithfully without dynamic error.
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90.
Trickling ﬁlter is an
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Answer: C —
Aerobic attached growth process
A trickling filter is a fixed-film (attached growth) aerobic biological treatment process.
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91.
Blue Baby syndrome is due to the presence of excess _______ in drinking water.
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Answer: D —
Nitrates
Methemoglobinemia, or Blue Baby syndrome, is caused by high nitrate levels in drinking water.
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92.
BOD is used as a characteristic of
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Answer: C —
Industrial eﬄuents
Biochemical Oxygen Demand (BOD) is a standard measure for the organic pollution load in industrial effluents.
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93.
The angle between the solar collector surface plane and the horizontal plane is called
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Answer: D —
Tilt angle
The tilt angle is the angle between the collector surface and the horizontal plane.
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94.
Main product obtained from fermentation of biomass is
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Answer: B —
Ethanol
Industrial fermentation of sugar and starch-rich biomass primarily produces ethanol.
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95.
Permanent hardness of water can be removed by
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Answer: D —
Ion exchange
Ion exchange is a common method for removing both temporary and permanent hardness from water.
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96.
Electrodialysis removes
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Answer: B —
Dissolved solids from water
Electrodialysis is a membrane process used to remove dissolved ions (salts) from water.
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97.
The permissible pH of drinking water is
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Answer: B —
6.5-8.5
The standard permissible pH range for drinking water is typically 6.5 to 8.5.
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98.
Which of the following is not a method of disinfection of water?
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Answer: D —
Filtration
Filtration is a physical separation process, not a disinfection method, although it can remove some microorganisms.
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99.
What is the power in wind, if velocity of the wind is 20 m/s and the blade length is 60 m. Assume air density as 1.23 kg/ $m^3$
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Answer: A —
55.64 MW
Power $P = 0.5 \times \rho \times A \times v^3$ . Area $A = \pi \times r^2 = \pi \times 60^2$ . $P = 0.5 \times 1.23 \times (\pi \times 3600) \times 20^3 \approx 55.64$ MW.
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