Description : How do I calculate capillary entry pressure for a given pore width and and a known surface tension?
Last Answer : I’m not a scientist but I did have a flash of intuition while reading your question. Must not these calculations have been made when the type of waterproof/breathable fabric that admits vapor but not water? The patents are certainly public.
Description : (a) Draw a diagram to show open stomatal pore and label on it: (i) guard cells (ii) chloroplast (b) State two functions of stomata. (c) How do guard cells regulate the opening and closing of stomatal pore? -Biology
Last Answer : (a) (b) Two functions of stomata are: (i) Exchange of gases between the plant and the atmosphere takes place through stomata. (ii)Transpiration in plants takes place through stomata. ( ... through these stomata, the plant closes these pores when it does not require carbon dioxide for photosynthesis.
Description : Minute pore found on the soft aerial part of plant especially the leaves are called? -Do You Know?
Last Answer : answer:
Description : What does pore mean ?
Last Answer : pore means to thicken.
Description : Gastrula has a pore known as
Last Answer : Gastrula has a pore known as A. Zoospore B. Oospore C. Gonospore D. Blastopore.
Description : Blastopore is the pore of :-
Last Answer : Blastopore is the pore of :- A. Archenteron B. Blastocoel C. Coelom D. acoelom
Description : The maximum pore space are found in
Last Answer : Ans. Clay soil
Description : The special modified epiderniai cells surrounding stomatal pore are called - (1) Epithelial cells (2) Guard cells (3) Subsidiary cells (4) Accessory cells
Last Answer : (2) Guard cells Explanation: The pore is bordered by a pair of specialized parenchyma cells known as guard cells that are responsible for regulating the size of the opening. Guard cells are specialized cells in the epidermis of leaves, stems and other organs that are used to control gas exchange.
Description : In dicots the pollen-grains possess : (1) two germ pores (2) three germ pores (3) four germ pores (4) one germ pore
Last Answer : (2) three germ pores Explanation: Pollen grains of monocots have one opening, while pollen grains of dicots have three openings. Pollengrains can be monocolpate (having one germ pore called germinal furrow e.g., monocots), bicolpate (2 germ pores) and tricolpate (3 germ pores e.g., dicots).
Description : Minute pore found on the soft aerial part of plant especially the leaves are called?
Last Answer : Stomata
Description : The Knudsen diffusivity is dependent on the (A) Molecular velocity only (B) Pore radius of the catalyst only (C) Molecular mean free path only (D) Molecular velocity and pore radius of the catalyst
Last Answer : (D) Molecular velocity and pore radius of the catalyst
Description : Pore size of the molecular sieve 5A is __________ mm. (A) 5 (B) 0.5 (C) 0.05 (D) 50
Last Answer : (B) 0.5
Description : Blastopore is the pore of (a) archenteron (b) blastocoel (c) coelom (d) alimentary canal.
Last Answer : (a) archenteron
Description : What is the function of germ pore? (a) Emergence of radicle (b) Absorption of water for seed germination (c) Initiation of pollen tube (d) Release of male gametes
Last Answer : (c) Initiation of pollen tube
Description : In guard cells when sugar is converted into starch, the stomatal pore (a) closes completely (b) opens partially (c) opens fully (d) remains unchanged.
Last Answer : a) closes completely
Description : In which one of the following, the genus name, its two characters and its phylum are not correctly matched, whereas the remaining three are correct? (a) Pila (i) Body segmented Mollusca ... Porifera (ii) Canal system (d) Periplaneta (i) Jointed appendages Arthropoda (ii) Chitinous exoskeleton
Last Answer : (a) Pila (i) Body segmented Mollusca (ii) Mouth with radula
Description : What is the Thiele modulus of the solid catalysed first order reaction as shown in the bellow figure, if the pore diffusion offers negligible resistance to reaction? (A) < 5 (B) < 0.5 (C) > 1 (D) 5
Last Answer : (B) < 0.5
Description : Pick out the correct statement. (A) A lower temperature favours the reaction of lower activation energy (B) The dispersion number for a reactor/vessel is uL/D (C) The rate controlling step in ... step (D) Pore volume and porosity of a catalyst is measured by BrunauerEmmett-Teller (BET) technique
Last Answer : (A) A lower temperature favours the reaction of lower activation energy
Description : Which of the following factors control the deactivation of a porous catalyst pellet? (A) Decay reactions (B) Pore diffusion (C) Form of surface attack by poison (D) All (A), (B) and (C)
Last Answer : (D) All (A), (B) and (C)
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 : Which one is the rate controlling step in a solid-gas non-catalytic reaction occurring at very high temperature? (A) Pore diffusion (B) Film diffusion (C) Ash layer diffusion (D) Chemical reaction
Last Answer : (B) Film diffusion
Description : In solid catalysed reactions the diffusional effects are more likely to affect the overall rate of reaction for (A) Fast reactions in catalyst of small pore diameter (B) Fast reaction in catalyst ... reactions in catalyst of small pore diameter (D) Slow reactions in catalyst of large pore diameter
Last Answer : (C) Slow reactions in catalyst of small pore diameter
Description : If the pore diffusion controls in a catalytic reaction, the apparent activation energy Ea is equal to (A) The intrinsic activation energy E (B) (E + ED) where ED is activation due to diffusion (C) (E + ED)/2 (D) ED/2
Last Answer : (D) ED/2
Description : If the catalyst pore size is small in comparison with the mean free path, collisions with the pore wall controls the process'. The diffusivity under this condition is called 'Knudsen diffusivity', which is affected by the (A) Pressure (B) Temperature (C) Both (A) & (B) (D) Neither (A) nor (B)
Last Answer : (B) Temperature
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 : Pick out the wrong statement. (A) Exit age description function (E) and internal age distribution function (I) are related as, E = -(dI/dθ) (B) Chemisorption studies are useful in the ... energy (D) A catalyst increases the potential energy barrier over which the reactants must pass to form products
Last Answer : (D) A catalyst increases the potential energy barrier over which the reactants must pass to form products
Description : If Thiele modulus is __________, then the pore diffusion resistance in a catalyst may be considered as negligible. (A) 0 (B) ∞ (C) < 0.5 (D) > 0.5
Last Answer : (C) < 0.5
Description : Helium-mercury method can be used to determine the __________ of the catalyst particle. (A) Pore volume (B) Solid density (C) Porosity (D) All (A), (B), & (C)
Last Answer : (D) All (A), (B), & (C)
Description : Which of the following resistances is not involved in a gas phase catalytic (gas-solid) reaction? (A) Ash resistance (B) Gas film and pore surface diffusion resistances for reactants (C) Surface phenomenon resistance (D) Gas film and pore surface diffusion resistances for products
Last Answer : (A) Ash resistance
Description : Helium-mercury method is used for the measurement of the __________ of the catalyst. (A) Surface area (B) Porosity (C) Pore volume (D) Both (B) & (C)
Last Answer : (D) Both (B) & (C)
Description : If pore diffusion is the controlling step in a solid catalysed reaction, the catalyst (A) Porosity is very important (B) Porosity is of less importance (C) Internal surface area is utilised efficiently (D) None of these
Last Answer : (B) Porosity is of less importance
Description : BET apparatus is used to determine the (A) Specific surface of a porous catalyst (B) Pore size distribution (C) Pore diameter (D) Porosity of the catalyst bed
Last Answer : (A) Specific surface of a porous catalyst
Description : Effectiveness factor of a catalyst pellet is a measure of the __________ resistance. (A) Pore diffusion (B) Gas film (C) Chemical reaction (D) None of these
Last Answer : (A) Pore diffusion
Description : Bulk diffusion in catalyst pore __________ with increase in pressure. (A) Increases (B) Decreases (C) Remains unchanged (D) Increases exponentially
Last Answer : (B) Decreases
Description : . B.E.T. method can be used to determine the __________ of a porous catalyst. (A) Solid density (B) Pore volume (C) Surface area (D) All (A), (B) and (C)
Last Answer : (C) Surface area
Description : Lowest pore space percentage recorded in — soil a. Clay b. Clay loam c. Loamy d. Sandy
Last Answer : d. Sandy
Description : Effectiveness factor (E) of a catalyst pellet is defined as, E = (actual rate within pore of the catalyst)/(rate if not snowed by pore diffusion), Effectiveness factor for a first order reaction is given by (where, T = Thiele modulus) (A) tan hT/T (B) tan T/T (C) tan hT/tan T (D) None of these
Last Answer : (A) tan hT/T
Description : If a solid-gas non-catalytic reaction occurs at very high temperature, the rate controlling step is the __________ diffusion. (A) Film (B) Ash layer (C) Pore (D) None of these
Last Answer : (A) Film
Description : Brunauer, Emmet and Teller (BET) equation is used to determine the specific surface area of a porous particle but not the pore volume & the porosity of the catalyst bed. Which of the following postulates ... (except the first one) is involved in each of the evaporation process (D) None of these
Last Answer : (B) There is no dynamic equilibrium between successive layer
Description : .Which is most likely to be exposed on the surface of a gram-negative bacterium? A.Pore protein (porin) B.Protein involved in energy generation C.Lipoteichoic acid D.Phospholipids
Last Answer : A.Pore protein (porin)
Description : Which is most likely to be exposed on the surface of a gram-negative bacterium? A- Pore protein (porin) B- Protein involved in energy generation C- .Lipoteichoic acid D- Phospholipids
Last Answer : Pore protein (porin)
Description : The compression resulting from a long term static load and consequent escape of pore water, is known as (A) Compaction (B) Consolidation (C) Swelling (D) None of these
Last Answer : (B) Consolidation
Description : During the first stage of triaxial test when the cell pressure is increased from 0.10 N/mm² to 0.26 N/mm², the pore water pressure increases from 0.07 N/mm² to 0.15 N/mm². Skempton's pore B (A) 0.5 (B) -0.5 (C) 2.0 (D) -2.0
Last Answer : (A) 0.5
Description : For shear strength, triaxial shear test is suitable because (A) It can be performed under all three drainage conditions (B) Precise measurement of the pore pressure and volume change during the test is possible (C) Stress distribution on the failure plane, is uniform (D) All the above
Last Answer : (D) All the above
Description : If the water table rises upto ground surface, then the (A) Effective stress is reduced due to decrease in total stress only but pore water pressure does not change (B) Effective stress is ... D) Total stress is increased due to decrease in pore water pressure but effective stress does not change
Last Answer : (B) Effective stress is reduced due to increase in pore water pressure only but total stress does not change
Description : The slope of isochrone at any point at a given time indicates the rate of change of (A) Effective stress with time (B) Effective stress with depth (C) Pore water pressure with depth (D) Pore water pressure with time
Last Answer : Answer: Option C
Description : Pick up the incorrect statement from the following: (A) The smaller the size of the pores, the higher the water can rise above the water table (B) Below the water table, the pore water may be static (C) The hydrostatic pressure depends on the depth below the water level (D) None of these
Last Answer : Answer: Option D
Description : The direct shear test suffers from the following disadvantage: (A) Drain condition cannot be controlled (B) Pore water pressure cannot be measured (C) Shear stress on the failure plane is not uniform (D) The area under the shear and vertical loads does not remain constant throughout the test
Description : The pressure that builds up in pore water due to load increment on the soil, is termed (A) Excess pore pressure (B) Excess hydrostatic pressure (C) Hydrodynamic pressure (D) All the above