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Right choice is (b) Complex mixtures

Explanation: CHROMATOGRAPHY is a physical method that is used to SEPARATE complex mixtures. The MIXTURE of different components is FLUSHED through the SYSTEM at different rates.

Correct choice is (a) Column chromatography

To elaborate: In Column chromatography, the STATIONARY phase held in a narrow tube and the MOBILE phase is forced through it under pressure. It is carried out in a long GLASS column having a stop-cock near the bottom.

The correct choice is (a) Solid or liquid

The explanation: In CHROMATOGRAPHY, there are two PHASES NAMELY, stationary PHASE and mobile phase. The stationary phase can be solid or a liquid SUPPORTED on a solid.

Correct ANSWER is (d) Potassium permanganate

Explanation: The given options are all examples of adsorbents in Column ADSORPTION except potassium permanganate. Some other adsorbents are STARCH and CHROMATOGRAPHIC purified siliceous EARTH.

The CORRECT choice is (c) THIN layer

Easy EXPLANATION: Thin layer chromatography involves the SEPARATION of substances of a mixture over a 0.2mm THICK layer (thin layer) of an adsorbent. The adsorbent can be silica gel or alumina.

The correct choice is (B) False

For EXPLANATION I would say: Chromatography can be used to purify volatile substances if the CARRIER fluid, OPERATING conditions and right ADSORBENT material are employed.

Right answer is (B) False

The best EXPLANATION: Chromatography can be used to separate delicate PRODUCTS. This is because chromatography is not performed under SEVERE conditions.

Right choice is (a) Solid, liquid

Best explanation: In Column chromatography, the STATIONARY phase is MADE of solid and the mobile phase is made of liquid. It is carried out in a LONG glass column which has a stop-cock near the bottom.

Right choice is (C) Radial paper chromatography

Easiest EXPLANATION: In Radial paper chromatography, the mobile phase moves HORIZONTALLY over a circular sheet of paper. Separation TAKES place based on partition.

Right answer is (a) Solid, liquid

Explanation: In Thin layer CHROMATOGRAPHY, the STATIONARY PHASE is MADE of solid and the MOBILE phase is made of liquid.

Correct ANSWER is (C) Either in COLUMNS or on plane surfaces

To explain I would say: Liquid chromatography can be performed either in columns or on plane surfaces. It could be liquid-solid chromatography or liquid-liquid chromatography.

Right option is (a) Only in COLUMNS

The BEST I can explain: GAS CHROMATOGRAPHY can be PERFORMED only in columns. It could be gas-solid chromatography or gas-liquid chromatography.

The correct choice is (d) PLANAR Chromatography

The best I can explain: In Planar Chromatography, the STATIONARY phase is supported on a flat plate of paper. The MOBILE phase moves by the influence of gravity or capillary ACTION.

The CORRECT choice is (b) SEPARATION in the column

The best I can explain: The OPERATION that occurs after the INJECTION of feed is a separation in the column. After that, elution from the column and detection of COMPONENTS takes place.

Correct option is (a) True

To elaborate: Different components will adsorb to the stationary phase in VARYING DEGREES. Components with a strong attraction to the SUPPORT move more slowly than components with weak attraction.

Correct OPTION is (b) Components with least affinity ELUTE first

To explain: During the elution phase, different components elute at different TIMES. Components with least affinity elute first.

Correct OPTION is (b) Amount of component in the sample

Explanation: Chromatogram is a detector that RESPONDS to concentration solute and is PLACED at the end of the column. The area under the PEAK can be used to DETERMINE the amount of component in the sample.

Correct answer is (a) True

Easiest explanation: The stationary phase COULD be a viscous liquid coated over a SURFACE of solid PARTICLES. The solid particles can ALSO be the stationary phase.

Correct option is (c) Y

To elaborate: Y will elute from the column first. COMPONENTS with LEAST AFFINITY to the stationary phase will elute first.

The correct choice is (c) Concentration

The best explanation: Using Chromatogram as a DETECTOR in Chromatography, a GRAPH is obtained between concentration and time. The detector is PLACED at the bottom of the column.

The CORRECT ANSWER is (c) GRAVITY

The best I can explain: In OLDER analytical methods, gravity facilitated the movement of the mobile phase. The effect of capillary action was also employed to allow movement.

Right choice is (d) Retention time

To EXPLAIN: The time taken by the analyte after sample INJECTION to reach the detector is called retention time. The retention of a SOLUTE in the system can be USED to IDENTIFY the solute.

Right answer is (a) Directly proportional

The EXPLANATION is: In chromatography, molar concentration of solute in STATIONARY phase is directly proportional to molar concentration of solute in mobile phase.

Cs α CM

Cs = k Cm

‘k’ is the distribution constant.

The correct choice is (d) Detector

To explain I WOULD say: The UNMARKED COMPONENT is detector. It is placed at the BOTTOM of the column. It responds to solute concentration.

Correct OPTION is (a) Dead TIME

Explanation: The time required for a molecule of the MOBILE phase to pass through the column is called dead time. The EFFECTIVENESS of the system depends on dead time.

Correct CHOICE is (c) DEAD time and retention time

Best explanation: ADJUSTED retention time is the remaining retention time after subtracting dead time from retention time. It AFFECTS the effectiveness of the system.

The CORRECT answer is (B) Expensive

The explanation is: Helium is expensive. Its ADVANTAGES are that it has low density and it ALLOWS greater flow rates.

The CORRECT answer is (a) True

Best explanation: Retention FACTOR is also known as the CAPACITANCE factor. It can be DENOTED as k’.

The correct OPTION is (b) Retention volume

To explain I would SAY: Retention volume is the volume of mobile phase REQUIRED to make a solute band move from the POINT of INJECTION through the column to the detector.

Right choice is (d) SENSITIVE to the changes in the flow rate of a carrier gas

To elaborate: The detector used in gas CHROMATOGRAPHY must be insensitive to the changes in flow rate of carrier gas. There are MANY detectors used in gas chromatography.

The correct option is (c) Graphite

Explanation: Graphite is not used as a HEATING element in Thermal conductivity detector. PLATINUM, GOLD and tungsten wire are used as heating ELEMENTS.

Correct CHOICE is (d) Detector response time increases

Easy EXPLANATION: Detector response time increases in narrow bore COLUMNS. HIGH purity SOLVENTS must be used in these columns.

Correct OPTION is (B) There is no need to vaporise the SAMPLES

Explanation: In HIGH pressure liquid chromatography (HPLC), samples need to be vaporised. It has high sensitivity.

Right option is (a) λ dM

For explanation I would SAY: EDDY diffusion is given as, A = λ DP. It is also CALLED MULTIPATH term.

Right choice is (C) Requirement of small particle size and HIGH pressure drop

The best EXPLANATION: The practical problems that arise due to a decrease in column diameter are the requirement of small particle size and high pressure drop. But, it increases column EFFICIENCY.

Right OPTION is (d) CAPILLARY COLUMN

Explanation: Capillary column is USED in gas CHROMATOGRAPHY. Analytical column is also known as a separation column.

Right choice is (c) Scanning wavelength detector

Explanation: Scanning wavelength detector provides a real TIME spectrum of the COMPONENT of interest. UV VISIBLE detector is the most widely USED detection SYSTEM.

Correct ANSWER is (d) Absorption

To explain I would SAY: Refractive index DETECTORS USED in liquid chromatography are not dependent on absorption. It DEPENDS on reflection, refraction and interference.

Correct choice is (a) Average linear rate of solute migration

Explanation: Average linear rate of solute migration is the RATIO of a length of column PACKING to retention TIME. It influences the EFFECTIVENESS of the column in SEPARATING solutes.

Right ANSWER is (C) 1

The best explanation: For an unpacked coated capillary COLUMN, the VALUE of the obstruction factor is 1. For a PACKED column, the value is 0.6.

Correct choice is (c) Photo IONIZATION DETECTOR

To explain I would say: Photo ionization detector uses ultraviolet radiation from lamps to produce ionisation of solute molecules. The CURRENT produced is MEASURED and RECORDED.

The correct answer is (c) It allows particles that cause precipitation upon CONTACT with stationary or mobile phase

To explain I would SAY: GUARD column removes particles that cause precipitation upon contact with stationary or mobile phase. It is PLACED before the separation column.

The correct OPTION is (d) Radioactive β- emitter

The EXPLANATION is: The UNMARKED component is Radioactive β- emitter. NITROGEN and HYDROGEN are the best carrier gases for these detectors.

The correct choice is (c) Silica

The best I can EXPLAIN: The CELLS in UV-Visible DETECTORS are MADE of QUARTZ, KELF and Teflon. They are not made of silica.

Correct choice is (b) Phosphorous

To explain: Thermionic EMISSION detector USED in gas chromatography is most SENSITIVE to phosphorous. It is 500 times more sensitive to phosphorous than FLAME ionization detector.