Question 88 - In the calculation of the growth of bacteria, colony forming unit (CFU) in serial dilution is used. In a laboratory, viable count assay is used to estimate CFU. Formula applied is CFU / mL = (number of colonies x dilution) / (amount plated, in unit mL). Acceptable plate count is either between 20 and 200 or between 30 and 300 according to 2 different references. A wastewater sample of 200 ml is added to and mixed with 1.8 L of sterile water. Another 200 ml of the mixture is added to and mixed with 1.8 L of sterile water. (a) Calculate the dilution of first mixture and the dilution of the second mixture. (b) 100 microlitres of wastewater samples from the first mixture and the second mixture are placed separately on 2 different alga plates. The first plate has 250 colonies and the second plate has 23 colonies. Calculate the average CFU / mL.

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What are the advantages and disadvantages of using gear pumps?

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Please help me send me questions for HPCL written test of Chemical Branch.I will be highly thankful to u...

0 Answers   TCE,

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Why methanol like petroleum compounds are stored in underground storage tanks?

2 Answers   MPCL, NFIL, Reliance, UPL,

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oil field interview question

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which is more effective , a single extraction with a large volume of solvent or several small volume extractions? Explain.

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ACCOUNTING AND FINANCIAL ENGINEERING - EXAMPLE 34.6 : In a random walk, a stochastic process starts off with a score of A. This is a score for a chemical engineering test. At each discrete event, there is probability p chance you will increase your score by B and a (1 - p) chance you will decrease your score by C. The event happens T times. Let D = expected value of score. (a) Form an equation of D as a function of A, B, C, T and p. (b) Find the value of D if A = 60, B = 1, C = -1, T = 50, p = 0.5.

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CHEMICAL ENERGY BALANCE - EXAMPLE 11.5 : According to Margules Equation, P = x(1) p(1) g(1) + x(2) p(2) g(2) for a two-component mixture where P is bubble pressure, x is mole fraction, p is saturation pressure, g is constant given by ln g(1) = x(2) A x(2). Find the value of A as a constant when P = 1.08 bar, p(1) = 0.82 bar, p(2) = 1.93 bar in a 50 : 50 mole fraction mixture. Estimate the pressure required to completely liquefy the 30 : 70 mixture using the same equation, by proving P = 1.39 bar. Take note that ln g(2) = x(1) A x(1), ln g(1) = x(2) A x(2).

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what is the difference between distillation column and distillation tower?

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BIOCHEMICAL ENGINEERING INSTRUMENTATION - EXAMPLE 29.6 : In infrared spectrum, one of the factors affecting peak location is the mass of the atoms. The stretching frequency of a bond connected to a lighter atom will be greater than the same bond connected to a heavier atom. (a) For halogens like florine (F), chlorine (Cl), bromine (Br), iodine (I) and astatine (At), what is their IUPAC group number? Hint : The proton numbers for F, Cl, Br, I and At are 9, 17, 35, 53 and 85 respectively. (b) For the compounds of H-F, H-Cl, H-Br, H-I and H-At, which one has the lowest stretching frequency and which one has the highest stretching frequency? State the reasons.

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Question 55 - The differential equation is 3 dy / dt + 2y = 1 with y(0) = 1. (a) The Laplace transformation, L for given terms are : L (dy / dt) = sY(s) - y(0), L(y) = Y(s), L(1) = 1 / s. Use such transformation to find Y(s). (b) The initial value theorem states that : When t approaches 0 for a function of y(t), it is equal to a function of sY(s) when s approaches infinity. Use the initial value theorem as a check to the answer found in part (a).

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what is the differance between Horizental and vertical heat exchanger?

11 Answers   Bihar Caustic and Chemicals,

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