Description : If dp is the equivalent diameter of a non-spherical particle, Vp its volume and sp its surface area, then its sphericity is φs is defined by (A) φs = 6 Vp /dpsp (B) φs = Vp /dpsp (C) φs = 6 dpSp /Vp (D) φs = dpSp /Vp
Last Answer : (A) φs = 6 Vp /dpsp
Description : A bed of spherical particles (specific gravity 2.5) of uniform size 1500 μm is 0.5 m in diameter and 0.5 m high. In packed bed state, the porosity may be taken as 0.4. Ergun's equation for the above fluid-particle ... fluidisation velocity, VOM is (A) 12 mm/s (B) 16 mm/s (C) 24 mm/s (D) 28 mm/s
Last Answer : (B) 16 mm/s
Description : A bed of spherical particles (specific gravity 2.5) of uniform size 1500 μm is 0.5 m in diameter and 0.5 m high. In packed bed state, the porosity may be taken as 0.4. Ergun's equation for the above fluid-particle system ... What is the porosity of the fluidised bed? (A) 0.2 (B) 0.5 (C) 0.7 (D) 0.8
Last Answer : (C) 0.7
Description : The specific surface of spherical particles is given by (where D and ρ are diameter and density of particle). (A) 6/D.ρ (B) 2/D.ρ (C) 4/D.ρ (D) 12/D.ρ
Last Answer : (A) 6/D.ρ
Description : For the non catalytic reaction of particles with surrounding fluid, the same needed to achieve the same fractional conversion for particles of different unchanging sizes is proportional to the particle diameter, when the ... through ash layer (C) Chemical reaction (D) Either (A), (B) or (C)
Last Answer : (C) Chemical reaction
Description : For the non-catalytic reaction of particles with surrounding fluid, the time needed to achieve the same fractional conversion for particles of different but unchanging sizes is proportional to the square of particle diameter, ... through ash layer (C) Chemical reaction (D) Either (A), (B) or (C)
Last Answer : (B) Diffusion through ash layer
Description : Power required to drive a ball mill with a particular ball load is proportional to (where, D = diameter of ball mill.) (A) D (B) 1/D (C) D2.5 (D) 1/D2.5
Last Answer : (C) D2.5 (D) 1/D2
Description : For pipe flows, head is proportional to __________ at constant capacity(where, D = pipe diameter). (A) 1/D (B) 1/D2 (C) 1/D5 (D) D
Last Answer : (C) 1/D5
Description : Sphericity for a non-spherical particle is given by (where, V and S are volume and surface area respectively of one particle. and, D = equivalent diameter of particle). (A) 6.V/D.S (B) V/6D.S (C) D.S/V (D) V/D.S
Last Answer : (B) V/6D.S (C) D.S/V (D) V/D.S
Description : Bond crushing law (A) Calls for relatively less energy for the smaller product particles, than does the Rittinger law (B) Is less realistic in estimating the power requirements of commercial crushers ( ... (D) States that the work required for the crushing is proportional to the new surface created
Last Answer : (A) Calls for relatively less energy for the smaller product particles, than does the Rittinger law
Description : In the Newton's law range, the terminal velocity of a solid spherical particle falling through a stationary fluid mass is __________ the fluid viscosity. (A) Directly proportional to (B) Inversely proportional to (C) Inversely proportional to the square root of (D) Independent of
Last Answer : (B) Inversely proportional to
Description : The terminal velocity of a solid spherical particle falling through a stationary fluid mass in the Stoke's law range is proportional to the (A) Inverse of fluid viscosity (B) Square of particle size (C) Difference in the densities of the particle & fluid (D) All (A), (B) and (C)
Last Answer : (D) All (A), (B) and (C)
Description : For motion of spherical particles in a stationary fluid, the drag coefficient in hindered settling compared to that in free settling is (A) More (B) Less (C) Equal (D) More or less, depending on the type of particle
Last Answer : (A) More
Description : At low Reynold's number, the power (P) required for agitating a fluid in a stirred tank becomes independent of inertial forces. In this limit, indicate which of the following relations is satisfied: Po = ρ/ρN3 D5 : Power number Re = ρ N D2 ... Re -1.0 (B) Po ∝ Re 0.0 (C) Po ∝ Re 0.5 (D) Po ∝ Re 1.0
Last Answer : (B) Po ∝ Re 0.0 (C) Po ∝ Re 0.5
Description : In Newton's law range, the terminal velocity of a solid spherical particle falling through a stationary fluid mass varies as the __________ of its diameter. (A) Inverse (B) Square root (C) Second power (D) First power
Last Answer : (B) Square root
Description : For spheres, the surface shape factor is given by (where, A = area, V = volume, and D = diameter) (A) π = (A/D2 ) (B) π/6 = (V/D3 ) (C) AD/V (D) None of these
Last Answer : (A) π = (A/D2 )
Description : The terminal velocity of a particle moving through a fluid varies as dp n . What is the value of n' for Newton's law regime? (A) 0.5 (B) 1 (C) 1.5 (D) 3
Last Answer : (A) 0.5
Description : The terminal velocity of a particle moving through a fluid varies as dp n . The value of n is equal to __________ in Stoke's law regime. (A) 1 (B) 0.5 (C) 2 (D) 1.5
Last Answer : (C) 2
Description : The settling velocity of a spherical particle of diameter less than 0.1 mm as per Stock’s law, is A. Vs = 418 (Gs – Gw) d [(3T + 70)/100] B. Vs = 418 (Gs – Gw)d² [(3T + 70)/100] C. Vs = 218 (Gs – Gw)d² [(3T + 70)/100] D. Vs = 218 (Gs – Gw)d [(3T + 70)/100]
Last Answer : ANS: B
Description : Half the angle of nip, (α), for a roll crusher is given by (where, dr, dp and df are diameters of crushing rolls, feed particles and rolls gap respectively). (A) cos α = (dr + dp)/(dr + df) (B) cos α = (dr + df)/(dr + dp) (C) tan α = (dr + dp)/(dr + df) (D) sin α = (dr + dp)/(dr + df)
Last Answer : (A) cos α = (dr + dp)/(dr + df)
Description : Bed pressure drop in an air fluidised bed of catalyst particles (ρp = 200 kg/m3, Dp = 0.05 cm) of 60 cm bed depth and bed porosity of 0.5 expressed in cm of water (manometer) is (A) 90 (B) 60 (C) 45 (D) 30
Last Answer : (B) 60
Description : A particle is settling in a liquid under Stokesian conditions. The free falling velocity of the particle is proportional to (A) √(Particle diameter) (B) Particle diameter (C) (Particle diameter)2 (D) (Particle diameter)3
Last Answer : B) Particle diameter
Description : According to the film theory of mass transfer, the mass transfer coefficient is proportional to (where, D = molecular diffusivity). (A) D (B) D2 (C) D0.5 (D) 1/D
Last Answer : (A) D
Description : For a non-spherical particle, the sphericity (A) Is defined as the ratio of surface area of a sphere having the same volume as the particle to the actual surface area of the particle (B) Has ... of volume of a sphere having the same surface area as the particle to the actual volume of the particle
Last Answer : (A) Is defined as the ratio of surface area of a sphere having the same volume as the particle to the actual surface area of the particle
Description : Sphericity is the ratio of the surface area of a spherical particle having the same volume as the particle to the surface area of the particle. Which of the following has the maximum value of sphericity? (A) Sphere (B) Cube (C) Cylinder (L/D = 1) (D) Raschig rings
Last Answer : (A) Sphere
Description : A spherical porous catalyst particle of radius R is subjected to reactant A which reacts to form B by a zero order surface reaction A → B. Film mass transfer resistance is negligible and pore diffusion of A ... (D) Effectiveness factor for a zero order reaction cannot be 7/8 as it must always be 1
Last Answer : (A) Inner catalyst core of radius R/8 does not participate in reaction (
Description : Drag co-efficient for motion of spherical particles in a stationary fluid in the stoke's law range is (A) 24/NRe,P (B) 16/NRe,P (C) 64/NRe,P (D) 48/NRe,P
Last Answer : (A) 24/NRe,P
Description : Rittinger's crushing law states that (A) Work required to form a particle of any size is proportional to the square of the surface to volume ratio of the product (B) Work required to form a ... ) For a given machine and feed, crushing efficiency is dependent on the size of the feed & product
Last Answer : (C) Work required in crushing is proportional to the new surface created
Description : A particle experiences constant acceleration for 20 seconds after starting from rest. If it travels a distance D1 in the first 10 seconds and distance D2 in the next 10 seconds then, (a) D2 = D1 (b) D2 = 2D1 (c) D2 = 3D1 (d) D2 = 4D1 -Science
Last Answer : (c) is the answer
Description : rpm of a trommel at critical speed is given by (where, D = Diameter of trommel in ft) (A) 76.65/D (B) 76.65/√D (C) 76.65/D2 (D) 76.75 √D
Last Answer : (B) 76.65/√D
Description : In a fully turbulent flow (Re > 10 5 ) in a pipe of diameter 'd', for a constant pressure gradient, the dependence of volumetric flow rate of an incompressible fluid is (A) d (B) d 2 (C) d 2.5 (D) d
Last Answer : (C) d 2.5
Description : Gibbs-Helmholtz equation is (A) ∆F = ∆H + T [∂(∆F)/∂T]P (B) ΔF = ΔH - TΔT (C) d(E - TS) T, V < 0 (D) dP/dT = ∆Hvap/T.∆Vvap
Last Answer : (A) ∆F = ∆H + T [∂(∆F)/∂T]P
Description : Pick out the Clausius-Clapeyron equation from the following: (A) dP/dT = ∆H/T∆V (B) ln P = - (∆H/RT) + constant (C) ∆F = ∆H + T [∂(∆F)/∂T]P (D) None of these
Last Answer : B) ln P = - (∆H/RT) + constant
Description : Which of the following is Clausius-Clapeyron Equation for vaporisation of an ideal gas under the condition that the molar volume of liquid is negligible compared to that of the vapor? (A) d ln p/dt = Hvap/RT2 (B) d ln p/dt = RT2/Hvap (C) dp/dt = RT2/Hvap (D) dp/dt = Hvap/RT2
Last Answer : (A) d ln p/dt = Hvap/RT2
Description : A particle A of diameter 10 microns settles in an oil of specific gravity 0.9 and viscosity 10 poise under Stoke's law. A particle B with diameter 20microns settling in the same oil will have a settling velocity (A) ... ) One fourth as that of A (C) Twice as that of A (D) Four times as that of A
Last Answer : (B) One fourth as that of A
Description : Power required by a centrifugal pump is proportional to (where, D = diameter, N = r.p.m) (A) N2D3 (B) ND2 (C) N2D (D) N3D5
Last Answer : (D) N3D5
Description : Capillary rise of mercury in a small diameter tube is proportional to (where, d = diameter of the tube, σ = surface tension of mercury) (A) d (B) 1/d (C) σ (D) 1/σ
Last Answer : (C) σ
Description : A compound pipe of diameter d1, d2 and d3 having lengths l1, l2 and l3 is to be replaced by an equivalent pipe of uniform diameter d and of the same length (l) as that of the compound pipe. The size of the equivalent pipe is given by (A) l/d² = + + (B) l/d³ = + ) + (C) = + + (D)
Last Answer : Answer: Option D
Description : The torque transmitted by a hollow shaft of outer diameter (D) and inner diameter (d) (a)π/4fs(D2-d2)/D (b) π/4fs(D3-d3)/D (c) π/4fs(D4-d4)/D (d) π/4fs(D4-d4)/D
Last Answer : (c) π/4fs(D4-d4)/D
Description : About 2-3 hp, power per gallon of a thin liquid provides vigorous agitation in an agitator. 'Power number' in agitation is given by (A) P. gc /n 3 . D2 . ρ (B) P. gc . ρ/µ
Last Answer : (A) P. gc /n 3 . D2 . ρ
Description : In Fig. 8.37, ABCD is a parallelogram and P, Q are the points on the diagonal BD such that BQ = DP. Show what APCQ is a parallelogram. -Maths 9th
Last Answer : Solution :-
Description : ABCD is a parallelogram in which P and Q are the mid-points of opposite sides AB and CD (Fig. 8.48). If AQ intersects DP at S and BQ intersects CP at R, show that -Maths 9th
Description : Let ABCD be a parallelogram. P is any point on the side AB. If DP and CP are joined in such a way that they bisect the angles -Maths 9th
Last Answer : answer:
Description : . Equivalent diameter of a particle is the diameter of the sphere having the same (A) Ratio of surface to volume as the actual volume (B) Ratio of volume to surface as the particle (C) Volume as the particle (D) None of these
Last Answer : (A) Ratio of surface to volume as the actual volume
Description : The importance of diffusion in a catalyst are increased by (A) Large catalyst particle size (B) An active surface of the catalyst (C) Small pore diameter (D) All (A), (B) and (C)
Description : Value of Nusselt number [Nu = (hD/k)] for the heat transfer byconduction from a droplet or a spherical particle to a surrounding stagnant film is (A) 0.5 (B) 2 (C) 10 (D) 100
Last Answer : (B) 2
Description : A spherical particle is falling slow in a viscous liquid such that Reynolds number is less than 1. Which statement is correct for this situation? (A) Inertial and drag forces are important (B) Drag ... forces are important (C) Drag force and gravitational forces are important (D) None of the above
Last Answer : (B) Drag, gravitational and buoyancy forces are important
Description : For the free settling of a spherical particle through a fluid, the slope of, CD-log NRe , plot is (A) 1 (B) -1 (C) 0.5 (D) -0.5
Last Answer : (B) -1
Description : In Newton's law range, the drag co-efficient for the motion of spherical particle in a stationary fluid is (A) 0.44 (B) 0.044 (C) 4.4 (D) 44
Last Answer : (A) 0.44
Description : For preparation of porous bearings by powder metallurgy, preferred particle shape is (A) Spherical (B) Nodular (C) Irregular (D) No preferred shape
Last Answer : (A) Spherical