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Correct choice is (c) PRECOAT (filter aid) filtration

The explanation is: A filter cake is FORMED by the substances that are retained on a filter. The filter cake grows in the course of filtration, becomes “THICKER” as particulate matter is being retained. With INCREASING layer thickness the flow resistance of the filter cake increases whereas membrane filters do not use any filter aid.

Right option is (c) Adsorption and Desorption

For explanation I would say: Adsorption means the attraction to a substance (as opposed to absorption, which means the COMPLETE envelopment of SOMETHING). Desorption is the opposite – when something is not attracted to the substance. How it relates to chromatography is through the mobile and stationary phase. Depending on what the substance adsorbs or desorbs to, will determine how it will move in the chromatogram. For EXAMPLE, if it adsorbs to the mobile phase, it will move a lot. HOWEVER, if it adsorbs to the stationary phase, it will not move very much. This is how mixtures are separated through chromatography, as different substances in the mixture will adsorb and desorb differently, and HENCE will move differently, and thus separation is achieved.

Right choice is (a) Screen/scroll centrifuge

Easiest EXPLANATION: For the filtration or the so-called screen centrifuge the drum is perforated and is inserted with a filter, for example a filter cloth, wire mesh or lot screen. The SUSPENSION flows through the filter and the drum with the perforated wall from the inside to the outside. In this WAY, the solid material is restrained and can be REMOVED. The KIND of removing depends on the type of centrifuge, for example manually or periodically.

Correct choice is (c) Microfiltration

Explanation: Microfiltration is a membrane filtration process which removes contaminants from a fluid by microporous membrane. The membrane pore size ranges from 0.1 to 10 micrometers. Microfiltration is DIFFERENT from reverse OSMOSIS and nanofiltration because it does not require pressure and does not remove dissolved contaminants. However, centrifugation is OFTEN effective when the particles are very small and DIFFICULT to filter.

The correct answer is (a) On increasing temperature, adsorption increases continuously

To explain I would say: PHYSISORPTION is EXOTHERMIC in NATURE. Therefore according to le chateliars principle, it occurs readily at low temperature and decreases with increase in temperature. Bond between adsorbent i.e. surface and adsorbate LIKE gases are WEAK so when temperature is increasing the bond get break easily and adsorption of adsorbate get stop so rate will decrease on increasing temperature.

Correct answer is (d) Based on separation of particles on size

Explanation: Rate-zonal CENTRIFUGATION is a centrifugation technique employed to effectively SEPARATE particles of DIFFERENT sizes. Once the centrifugation is over, fractions are COLLECTED.

Right ANSWER is (B) Ficoll

For explanation: Ficoll is a neutral, highly branched, high-mass, HYDROPHILIC polysaccharide which dissolves readily in aqueous solutions. Ficoll is part of Ficoll-Paque, which is used in biology laboratories to separate BLOOD to its components (erythrocytes, leukocytes, ETC.). Ficoll-Paque is normally placed at the bottom of a conical tube, and blood is then slowly layered above Ficoll-Paque.

Correct answer is (c) Gas centrifuge

For explanation: Gas centrifuges are USED in URANIUM enrichment. The HEAVIER isotope of uranium (uranium-238) in the uranium hexafluoride gas tends to concentrate at the walls of the centrifuge as it spins, while the desired uranium-235 isotope is extracted and CONCENTRATED with a scoop selectively placed INSIDE the centrifuge. It takes many thousands of centrifugations to enrich uranium enough for use in a nuclear reactor (around 3.5% enrichment), and many thousands more to enrich it to weapons-grade (above 90% enrichment) for use in nuclear weapons.

Right OPTION is (c) Differential centrifugation

Easy explanation: The simplest form of separation by centrifugation is differential centrifugation, sometimes called differential pelleting. Particles of different densities or sizes in a suspension will sediment at different rates, with the larger and denser particles sedimenting faster. These sedimentation rates can be increased by using centrifugal force. A suspension of CELLS subjected to a series of increasing centrifugal force cycles will yield a series of PELLETS containing cells of decreasing sedimentation rate.

Differential centrifugation is a common PROCEDURE in microbiology and cytology USED to separate certain organelles from whole cells for further analysis of specific parts of cells.

The correct option is (C) Estimate the efficiency of the column

Best explanation: The PLATE model SUPPOSES that the chromatographic column contains a large number of separate LAYERS, called THEORETICAL plates. Separate equilibrations of the sample between the stationary and mobile phase occur in these “plates”.

Right choice is (B) False

To explain I would SAY: Microfiltration cannot be used to remove viruses as a microfiltration filter has a pore size around 0.1 micron, so when WATER undergoes microfiltration, many microorganisms are removed, but viruses remain in the water. Ultra filtration would remove these larger particles, and may remove some viruses.

The correct choice is (a) 154.3 m^3/(m^2.d)

For EXPLANATION I would SAY: Select four FILTERS .

The SURFACE area for each filter is, a = 189 m^2/4 = 47.25 m^2

We can use 7 m×7 m or 6 m×8 m or 5.9 m×8 m (EXACT)

If a 7 m×7 m filter is installed, the normal filtration rate is

V = Q/A = (0.35 m^3/s×86,400s/d)/(4×7 m×7 m) = 154.3 m^3/(m^2.d)

The correct option is (b) SOLID and Liquid

The explanation is: Filtration is the separation of solids from liquids by forcing the liquid to flow through a porous medium and DEPOSITING the solids on the medium. A FILTER AID (finely divided material added to the liquid to be filtered) helps control flow and solids removal.

Precoat filtration is a type of mechanical filtration that can be used to CLARIFY liquids. Filter aids such as diatomaceous earth, perlite and cellulose enables a liquid to pass through while retaining the haze-causing particles.

The CORRECT choice is (b) False

Best explanation: Polar components will be ATTRACTED to the WATER molecules attached to the cellulose (paper) and not attracted to a nonpolar SOLVENT. The chromatogram will not CONTAIN the polar components, given that it doesn’t climb up the paper with the nonpolar solvent.

The correct answer is (a) Optimum column LENGTH

Explanation: The Van Deemter equation is an empirical formula describing the relationship between plate HEIGHT (H, the length needed for one theoretical plate) which is a measure of column efficiency, and linear velocity (µ) . Smaller plate height values correspond to greater peak efficiencies, as more plates, or analyte partitioning, can occur over a fixed length of a column. The Van Deemter equation is governed by three cumulative terms: (A) eddy diffusion, (B) LONGITUDINAL diffusion, and (C) mass transfer. A loss in peak efficiency can be observed as a wider analyte band, and therefore, these three terms can also be VIEWED as factors that CONTRIBUTE to band broadening.

The correct CHOICE is (a) True

The best EXPLANATION: THEORETICALLY, desorption curve is higher than adsorption curve in low PRESSURE area if the material is mesoporous (2-50nm). If the material is microporous (<2nm), both curves should be matched together.

Correct choice is (a) 4.5 × 10^-7 CM s^-2

For explanation I WOULD SAY: The centrifugal FIELD G, at a point 5 cm from the centre of rotation MAY be calculated using the equation G = ω^2 r,

G = (3000)^2 × 5 cm s^-2 = 4.5 × 10^-7 cm s^-2.

Correct OPTION is (d) 0.216 bar

Best EXPLANATION: Given data

p = 1.896cm^3g^-1 bar^-1

b = 0.146 bar^-1

Substitute in the CORRESPONDING EQUATION

The correct option is (a) Type 1 ADSORPTION ISOTHERM

To explain: The above graph depicts Monolayer adsorption. This graph can be easily explained using LANGMUIR Adsorption Isotherm. Examples of Type-I adsorption are Adsorption of Nitrogen (N2) or Hydrogen (H) on charcoal at TEMPERATURE near to -1800C.

Correct answer is (c) The pressure makes room ISOLATED from the surrounding and contaminants

To explain: Positive pressure refers to pressure that exceeds the surrounding pressure of any room, chamber or confined SPACE. Positive pressure is maintained in a closed ZONE to ENSURE no outside contaminated gaseous or LIQUID substance can get into that protected zone.

Right answer is (b) False

To explain: The “fictitious” force on everything that points opposite that of gravity,the effect of gravity is reduced. Many PARTICLES or cells in a liquid suspension, GIVEN time, will eventually settle at the bottom of a container DUE to gravity. However, the length of time required for such separations is impractical. Other particles, extremely small in size, will not separate at all in solution unless subjected to high centrifugal force.

Correct choice is (a) High- performance liquid chromatography (HPLC)

To EXPLAIN I would say: In order to achieve the high resolutions characteristic of HPLC, stationary-phase particles 2-5 μm in diameter are commonly used. Because the particles are so small, HPLC systems are operated under high pressure (5-10 MPa) to achieve flow rates of 1-5 ml MIN -1. FPLC INSTRUMENTS are not able to develop such high pressures (1-2 MPa) and are THEREFORE operated with column packings of larger size.

Correct choice is (d) Disc FILTER

The explanation is: Disc filter, this type of filter is FED continuously for a CERTAIN amount of TIME. Then feed is STOPPED and next batch steps follow, like cake wash, cake blow and cake discharge.

Right ANSWER is (b) Centrifugal force is 500 times greater than earthly gravitational force

The best explanation: CENTRIFUGE is any device that applies a sustained centrifugal force; that is, a force DUE to rotation. Effectively, the centrifuge SUBSTITUTES a similar, stronger, force for that of gravity.

When a suspension is rotated at a certain speed or revolutions per minute (RPM), centrifugal force causes the PARTICLES to move radially away from the axis of rotation. The force on the particles (compared to gravity) is called Relative Centrifugal Force (RCF). For example, an RCF of 500 x g indicates that the centrifugal force is 500 times greater than earthly gravitational force.

The correct choice is (b) Gel- filtration CHROMATOGRAPHY

Easy EXPLANATION: Gel filtration chromatography, a type of SIZE exclusion chromatography, can be used to either FRACTIONATE molecules and COMPLEXES in a sample into fractions with a particular size range, to remove all molecules larger than a particular size from the sample, or a combination of both operations.

Correct CHOICE is (b) Chromatogram

Explanation: The machine used is called a gas or liquid chromatograph, the data generated is called a chromatogram.It is an ELECTRONIC file or hardcopy CONTAINING the information generated during the chromatography run.

The correct option is (b) False

Easy EXPLANATION: As the feed rate is increased the LIQUID layer moving up the wall of the centrifuge becomes thicker; this reduces the performance of the centrifuge by increasing the distance a particle must travel to REACH the wall. Liquid from the feed spills over a weir at the top of the bowl. When the thickness of sediment COLLECTING in the bowl reaches the position of the liquid-overflow weir, SEPARATION efficiency declines rapidly. This limits the capacity of the centrifuge.

The correct answer is (d) Including intermittent USE of compressed AIR during the PROCESS.

To elaborate: In terms of WATER treatment, including water purification and sewage treatment, backwashing refers to pumping water backward through the filters media, sometimes including intermittent use of compressed air during the process. Backwashing is a form of preventive MAINTENANCE so that the filter media can be reused.

Correct answer is (b) The mobile PHASE is polar and stationary phase is non-polar

The BEST I can EXPLAIN: In reversed phase chromatography, the mobile phase is polar (like WATER), and the stationary phase is non-polar while in NORMAL phase chromatography, the mobile phase is non-polar (100% organic), and the stationary phase is polar.

Correct option is (c) Freundlich

To explain I would say: The Freundlich isotherm was the first isotherm model proposed for SORPTION processes. It can be applied for non ideal sorption on HETEROGENEOUS surfaces, as well as, MULTILAYER sorption. A variation in the slope between 0 and 1 is associated with a chemisorption process, which is more heterogeneous as the value gets CLOSER to 0. Due to the lack in fundamental thermodynamic basis, since there is no approach to Henry’s law at vanishing concentrations, this represents a limitation of this isotherm model.

Correct answer is (d) The migration rate of an ANALYTE through a column

Best explanation: k’ (Capacity factor) in the CHROMATOGRAPHY is to PROVIDE a calculation or formula which defines how much interaction the SOLUTE has with the stationary phase material. And it is based on the formula given below:

Where, T (R) = Retention time of the peak in minutes

T (0) = Retention time of an unretained peak

k’ value should be >1.

The correct answer is (a) Attachment

The best I can explain: Sorption is a PHYSICAL and CHEMICAL PROCESS by which ONE substance becomes ATTACHED to another. The reverse of sorption is desorption.

Correct option is (a) 2200-2500 RPM

For EXPLANATION I would say: Do not centrifuge immediately after drawing blood. Allow the blood to clot in an upright position for at LEAST 30 minutes but not longer than 1 hour before centrifugation. Perform venipuncture as with any other blood COLLECTION device. Centrifuge for at least 15 minutes at 2200-2500 RPM within one hour of collection.

Correct ANSWER is (c) 4188.8 rad s^-1

The best explanation: The angular VELOCITY, ω, may be calculated USING the equation:

ω = (2 π REV min-1)/60

ω = 2 × 3.1416 × 40000/60 rad s^-1

= 4188.8 rad s^-1.