Answer / amruthasesh

It is because the freezer when kept at top cools the circulated air in contact with it thus making it denser than the air below. Thus cooled air comes down and the hotter air being less dense moves up. Imagine if the freezer is at the bottom..circulation will not be possible as cold air being dense will continue to remain at the bottom and hot air being light will continue to be at the top. This is nothing but natural convection phenomena.

Answer / harish saini

Due to convection current

BIOPROCESS ENGINEERING - EXAMPLE 14.3 : The kinetic behavior of an enzyme could be described using Michalis - Menten equation : Vo = Vmax [S] / (Km + [S]). Derive this equation from [ES] = [E]total [S] / (Km + [S]), Vmax = Kcat [E]total, Vo = Kcat [ES].

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ENGINEERING MATERIAL - EXAMPLE 12.1 : In crystal material, hexagonal crystal system could form 4-digit index in certain direction of solid. For [1(-1)0] direction in the hexagonal crystal systems of particular catalyst applied in fume removal of incinerator, what is the four-digit index for this direction? Hint : The transformation equations between the 3-digit [h'k'l'] and the 4-digit [hkil] indices are : h = (1/3) (2h'-k'); i = - (h + k); k = (1/3) (2k'-h'); l = l' A. [(-1)100] B. [1(-1)00] C. [(-1)000] D. [00(-1)(-1)] E. [(-1)0(-1)0]

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PROCESS DESIGN - EXAMPLE 21.1 : According to rules of thumb in chemical process design, consider the use of an expander for reducing the pressure of a gas when more than 20 horsepowers can be recovered. The theoretical adiabatic horsepower (THp) for expanding a gas could be estimated from the equation : THp = Q [ Ti / (8130a) ] [ 1 - (Po / Pi) ^ a ] where 3 ^ 3 is 3 power 3 or 27, Q is volumetric flowrate in standard cubic feet per minute, Ti is inlet temperature in degree Rankine, a = (k - 1) / k where k = Cp / Cv, Po and Pi are reference and systemic pressures respectively. (a) Assume Cp / Cv = 1.4, Po = 14.7 psia, (temperature in degree Rankine) = [ (temperature in degree Celsius) + 273.15 ] (9 / 5), nitrogen gas at Pi = 90 psia and 25 degree Celsius flowing at Q = 230 standard cubic feet per minute is to be vented to the atmosphere. According to rules of thumb, should an expander or a valve be used? (b) Find the outlet temperature To by using the equation To = Ti (Po / Pi) ^ a.

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How can we identify a poisoned food if we are not able to sense it?? . .,(naturally by colour ,smell etc. . .)

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What is screen analysis?

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What is the meaning of the critical speed of a turbine, and what are its effects on the shaft line

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CHEMICAL FLUID MECHANIC - EXAMPLE 3.1 : Water flows through a pipe with circular cross sectional area at the rate of V / t = 80 L / s where V is the volume and t is time. Let Av = 80 L / s where A is cross sectional area and v is velocity of fluid. For point 1, the radius of the pipe is 16 cm. For point 2, the radius of the pipe is 8 cm. Find (a) the velocity at point 1; (b) the velocity at point 2; (c) the pressure at point 2 by using Bernoulli's equation where P + Rgy + 0.5 RV = constant. P is the pressure, R = density of fluid, V = square of fluid's velocity, g = gravitational constant of 9.81 N / kg and y = 2 m = difference of height at 2 points. The pressure of point 1 is 180 kPa.

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i am giving BARC Trainee exam in chemical. Can anyone tell the syllabus and question paper pattern for OCES for BARC trainee?

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What is the order of a chemical reaction, , if the rate of formation of 'C', increases by a factor of 2.82 on doubling the concentration of 'A' and increases by a factor of 9 on trebling the concentration of 'B'?

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What is condensate lift?

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which chemical reaction has the maximum evolution of heat?

3 Answers   IOCL,

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UNIT OPERATION - EXAMPLE 9.1 : Which of the sequence below represent a feasible flows of ethanol processing plants using cellulose as starting material? A. raw material -> heat exchanger -> distillation column -> reactor. B. reactor -> distillation column -> raw material -> heat exchanger. C. heat exchanger -> raw material -> distillation column -> reactor. D. raw material -> heat exchanger -> reactor -> distillation column. E. distillation column -> raw material -> reactor -> heat exchanger.

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