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Experiments were conducted to determine the flux of a species A in a stagnant medium across a gas-liquid interface. The overall mass transfer co-efficient based on the liquid side for dilute systems for the above was estimated to be 4 × 10<sup>-3</sup> kg mole/m<sup>2</sup>.s. The equilibrium data for the system is given as y = 2x. The flux across the interface (in kg mole/m<sup>2</sup>.s) for bulk concentrations of A in gas phase and liquid phase as y = 0.4 and x = 0.01 respectively is
A
5.6 × 10<sup>-4</sup>
B
8.5 × 10<sup>-4</sup>
C
5.6 × 10<sup>-3</sup>
D
8.5 × 10<sup>-3</sup>
Correct Answer:
8.5 × 10<sup>-4</sup>
H
2
S is being absorbed in a gas absorber unit. The height of the transfer unit based on the overall mass transfer coefficient on the gas side is 0.4 m. The equilibrium data is given by, y = 1.5x. The bulk concentration of H
2
S has to be reduced from 0.05 to 0.001 mole fraction in the gas side. The height of the tower (in metres) corresponding to an operating line given by, y = 5x + 0.001 is
A
2.0
B
1.56
C
1.0
D
0.56
In a wetted-wall tower, an air-H2S mixture is flowing by a film of water which is flowing as a thin film down a vertical plate. The H2S is being absorbed from the air to the water at a total pressure of 1.50 atm abs and 30oC. The value of kc of 9.567×10-4 m/s has been predicted for the gas-phase mass-transfer coefficient. At a given point the mole fraction of H2S in the liquid at the liquid-gas interface is 2.0×10-5 and pA of H2S in the gas is 0.05 atm. The Henry’s law equilibrium relation is pA(atm) = 609xA (mole fraction in liquid). Calculate the rate of absorption of H2S.
A
1.480×10-3 kmol/m2.s
B
1.486×10-3 kmol/m2.s
For absolute chamber gas temperature Tg, absolute liquid temperature Tl, absolute wall temperature on the gas side of the wall Twg, overall film coefficient h, gas film coefficient hg and liquid film coefficient hl, determine the expression for heat transferred per unit area q.
A
q = hl (To – Twg)
B
q = h (To – Twg)
C
q = hg (To – Twg)
D
q = hg/h (Twg – To)
A stream of air at 100 kPa pressure and 300 K is flowing on the top surface of a thin flat sheet of solid naphthalene of length 0.2 m with a velocity of 20 m/sec. The other data are: Mass diffusivity of naphthalene vapor in air = 6 * 10 –6 m2/sec Kinematic viscosity of air = 1.5 * 10 –5 m2.sc Concentration of naphthalene at the air-solid naphthalene interface = 1 * 10 – 5 kmol/m3 Calculate the overage mass transfer coefficient over the flat plate. Note: For heat transfer over a flat plate, convective heat transfer coefficient for laminar flow can be calculated by the equation. Nu = 0.664 ReL1/2 Pr1/3 you may use analogy between mass and heat transfer.
A
0.014 m/sec
B
0.015 m/sec
C
0.016 m/sec
D
0.013 m/sec
The heat loss from unpainted aluminum side of a house has been calculated on the presumption that overall coefficient of heat transfer is 5 W/m 2 K. Later, it was discovered that the air pollution levels are such that fouling factor on this side is of the order of 0.0005 m2 K/W. Find overall heat transfer coefficient of dirty side
A
2.9875 W/m2 K
B
3.9875 W/m2 K
C
4.9875 W/m2 K
D
5.9875 W/m2 K
A single pass shell and tube heat exchanger, consisting of a bundle of 100 tubes (inner diameter 25 mm and thickness 2 mm) is used for heating 28 kg/s of water from 25 degree Celsius to 75 degree Celsius with the help of a steam condensing at atmospheric pressure on the shell side with condensing heat transfer coefficient 5000 W/m2 degree. Make calculation for overall heat transfer coefficient based on the inner area. Take fouling factor on the water side to be 0.002 m2 degree/W per tube and neglect effect of fouling factor on the shell side and thermal resistance of the tube wall
A
647.46 W/m2 degree
B
747.46 W/m2 degree
C
847.46 W/m2 degree
D
947.46 W/m2 degree
What is the monoisotopic and average mass of valine? Given data: Mass of the most abundant isotope of Carbon (C°)=12.0000, Mass of most abundant isotope of Hydrogen (H°)=1.0078, Mass of most abundant isotope of Oxygen (O°)=15.9949, Mass of most abundant isotope of Nitrogen (N°)=14.0031, The average mass of Carbon (C)=12.011, The average mass of Hydrogen (H)=1.008, The average mass of Oxygen (O)=15.999, The average mass of Nitrogen (N)=14.007.
A
99.068 and 99.2361
B
99.216 and 99.326
C
99.111 and 99.321
D
99.068 and 99.132
Read the passage carefully and choose the best answer to each question out of the four alternatives and click the button corresponding to it.
Ants have been living on the earth for more than 100 million years and can be found almost anywhere on the planet. It is estimated that there are about 20000 different species of ants. For this reason ants have been called Earth's most successful species. If you watch ants for any length of time you will see that they really do communicate with each other and very effectively too. Ants communicate by touching each other with their antennae. Ants also use chemicals called pheromones to leave scent trails for other ants to follow. Ants build many different types of homes. Many ants build simple little mounds out of dirt or sand. Other ants use small sticks mixed with dirt and sand to make a stronger mound that offers protection from rain. Western Harvester ants make a small mound on top, but then tunnels up to 15 feet straight down to hibernate during winter. Ant mounds consist of many chambers connected by tunnels. Different chambers are used for nurseries, food storage, and resting places for the worker ants. Some ants live in wood like termites. Army ants don't make a home at all but travel in a large groups searching for food. Ants are social insects which means they live in large colonies or groups. Some colonies consist of millions of ants. There are three types of ants in each species, the queen, the sterile female workers and males. The male ants only serve one purpose, to mate with future queen ants and do not live very long. The queen grows to adulthood, mates, and then spends rest of her life laying eggs. A colony may have only one queen, or there may be many queens depending on the species. Ants go through four stages of development: egg, larva, pupa and adult.
Why are ants called the 'Earth's' most successful species?
A
Because they have been on earth for more than a 100 million years
B
Because they can be found anywhere on earth
C
Because they have been on earth for more than a 100 million years and because they can be found anywhere on earth
D
Because there are 2000 different species of ants on earth
For absolute chamber gas temperature Tg, absolute liquid temperature Tl, overall film coefficient h, gas film coefficient hg and liquid film coefficient hl, determine the expression for heat transferred per unit area q.
A
q = h/(hg hl) x (Tg – Tl)
B
q = hg (Tg – Tl)
C
q = hghl/h x (Tg – Tl)
D
q = h (Tg – Tl)
Which of the following statements are true?
Statement I Big data refers to no precise quantity, but generally refers to data in the range of Petabytes and Exabyte, i.e. billions to trillions of records, all from various sources. Big data is generated much faster. than traditional data in much larger quantities.
Statement II Big data interests industries because they are able to learn more patterns and curious variances than smaller data sets, with the capability to provide valuable insights into consumer behaviour, weather systems, financial market activity, or other phenomena.
Statement III Various departments and product lines use various applications within most organisations and store data in separate datasets. These separate databases may contain similar data, but data from one data base to another is not always consistent. This is called data silo.
A
Both statements I and II
B
Both statements II and III
C
Both statements I and III
D
All of the above