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Multiple choice question for engineering

Set 1

1. Chromatography is a physical method that is used to separate and analyse __________
a) Simple mixtures
b) Complex mixtures
c) Viscous mixtures
d) Metals

View Answer

Answer: b [Reason:] 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.

2. In which type of chromatography, the stationary phase held in a narrow tube and the mobile phase is forced through it under pressure?
a) Column chromatography
b) Planar chromatography
c) Liquid chromatography
d) Gas chromatography

View Answer

Answer: a [Reason:] 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.

3. In chromatography, the stationary phase can be ___________ supported on a solid.
a) Solid or liquid
b) Liquid or gas
c) Solid only
d) Liquid only

View Answer

Answer: a [Reason:] In chromatography, there are two phases namely, stationary phase and mobile phase. The stationary phase can be solid or liquid supported on a solid.

4. In chromatography, which of the following can the mobile phase be made of?
a) Solid or liquid
b) Liquid or gas
c) Gas only
d) Liquid only

View Answer

Answer: b [Reason:] In chromatography, the mobile phase can be composed of liquid or gas. It cannot be a solid material.

5. Which of the following cannot be used as adsorbent in Column adsorption chromatography?
a) Magnesium oxide
b) Silica gel
c) Activated alumina
d) Potassium permanganate

View Answer

Answer: d [Reason:] The given options are all examples of adsorbents in Column adsorption except potassium permanganate. Some other adsorbents are starch and chromatographic purified siliceous earth.

6. Which of the following types of chromatography involves the separation of substances in a mixture over a 0.2mm thick layer of an adsorbent?
a) Gas liquid
b) Column
c) Thin layer
d) Paper

View Answer

Answer: c [Reason:] 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.

7. Chromatography cannot be used to purify volatile substances.
a) True
b) False

View Answer

Answer: b [Reason:] Chromatography can be used to purify volatile substances if the carrier fluid, operating conditions and right adsorbent material are employed.

8. In Column chromatography, the stationary phase is made of _________ and the mobile phase is made of _________
a) Solid, liquid
b) Liquid, liquid
c) Liquid, gas
d) Solid, gas

View Answer

Answer: a [Reason:] 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.

9. Chromatography cannot be used to separate delicate products.
a) True
b) False

View Answer

Answer: b [Reason:] Chromatography can be used to separate delicate products. This is because chromatography is not performed under severe conditions.

10. In Thin layer chromatography, the stationary phase is made of _________ and the mobile phase is made of _________
a) Solid, liquid
b) Liquid, liquid
c) Liquid, gas
d) Solid, gas

View Answer

Answer: a [Reason:] In Thin layer chromatography, the stationary phase is made of solid and the mobile phase is made of liquid.

11. In which of the following type of paper, chromatography does the mobile phase move horizontally over a circular sheet of paper?
a) Ascending paper chromatography
b) Descending paper chromatography
c) Radial paper chromatography
d) Ascending – descending chromatography

View Answer

Answer: c [Reason:] In Radial paper chromatography, the mobile phase moves horizontally over a circular sheet of paper. Separation takes place based on partition.

12. Liquid chromatography can be performed in which of the following ways?
a) Only in columns
b) Only on plane surfaces
c) Either in columns or on plane surfaces
d) Neither in columns nor on plane surfaces

View Answer

Answer: c [Reason:] Liquid chromatography can be performed either in columns or on plane surfaces. It could be liquid-solid chromatography or liquid-liquid chromatography.

13. Gas chromatography can be performed in which of the following ways?
a) Only in columns
b) Only on plane surfaces
c) Either in columns or on plane surfaces
d) Neither in columns nor on plane surfaces

View Answer

Answer: a [Reason:] Gas chromatography can be performed only in columns. It could be gas-solid chromatography or gas-liquid chromatography.

14. In Gas-liquid phase chromatography, the stationary phase is composed of _________ and the mobile phase is made of _________
a) Solid, liquid
b) Liquid, liquid
c) Liquid, gas
d) Solid, gas

View Answer

Answer: c [Reason:] In Gas-liquid phase chromatography, the stationary phase is made of liquid and the mobile phase is made of gas. Separation is based on partition.

15. Which of the following types of chromatography involves the process, where mobile phase moves through the stationary phase by the influence of gravity or capillary action?
a) Column Chromatography
b) High Pressure Liquid Chromatography
c) Gas Chromatography
d) Planar Chromatography

View Answer

Answer: d [Reason:] In Planar Chromatography, stationary phase is supported on flat plate of paper. The mobile phase moves by the influence of gravity or capillary action.

Set 2

1. In Saltzman method, which of the following are formed when air containing NO2 is passed in an
absorbing solution consisting of the sulphanilic acid and diamine dissolved in the acetic acid medium?
a) Blue colour dye complex
b) Green colour dye complex
c) Pink colour dye complex
d) Orange colour dye complex

View Answer

Answer: c [Reason:] In Saltzman method, a pink colour dye is formed when air containing NO2 is passed in an absorbing solution consisting of the sulphanilic acid and diamine dissolved in the acetic acid medium. It is sensitive in the ppm range.

2. NO can be analysed by converting it into NO2 and passing it through potassium permanganate. Which of the following is the main disadvantage of this method?
a) Less accuracy
b) Dye formed is unstable
c) Dye formed is colourless
d) Quantity of dye is low

View Answer

Answer: b [Reason:] NO can be analysed by converting it into NO2 and passing it through potassium permanganate. The main disadvantage of this method is that the dye formed is unstable. Hence, it is not suitable for collection of 24 hours sample.

3. In Jacob-Hochheiser method, NO2 is passed through a dilute solution of sodium hydroxide forming the nitrite ion. The nitrite ion is reacted with sulphanilamide and ethylene diamine in which of the following to form the highly coloured azo dye?
a) Sulphuric acid
b) Hydrochloric acid
c) Nitric acid
d) Phosphoric acid

View Answer

Answer: d [Reason:] In Jacob-Hochheiser method, NO2 is passed through a dilute solution of sodium hydroxide to form the nitrite ion. The nitrite ion is treated with sulphanilamide and ethylene diamine in phosphoric acid to form the highly coloured azo dye. Then, colorimetric analysis is done.

4. Which of the following methods results in the formation of yellow coloured compound?
a) Griess-Saltzman method
b) Phenoldisul phonoic acid method
c) Chemiluminescence method
d) West-Gaeke method

View Answer

Answer: b [Reason:] Phenoldisul phonoic acid method results in the formation of yellow coloured compound. The intensity of the colour is measured to determine the concentration of NOx.

5. Which of the following is the most common application of Chemiluminescence method used for the analysis of Nitrogen oxides?
a) In medical applications
b) In automotive exhaust gases
c) In manufacturing processes
d) In chemical industries

View Answer

Answer: b [Reason:] The most common application of Chemiluminescence method used for the analysis of Nitrogen oxides is to measure amount of NO in automotive exhaust gases. Chemiluminescence occurs due to the formation of new chemical bonds.

6. Which of the following is the wavelength at which CO laser operates?
a) 1.005 µm
b) 5.307 µm
c) 4.952 µm
d) 6.179 µm

View Answer

Answer: b [Reason:] CO laser operates at a wavelength of 5.307 µm. It is a DC-excited continuous working laser.

7. CO laser is operated at liquid nitrogen temperature.
a) True
b) False

View Answer

Answer: a [Reason:] CO laser is operated at liquid nitrogen temperature. It is a DC-excited continuous working laser.

8. The chemiluminescence reactor with ozonator is specific to which of the following compounds?
a) N2
b) NO
c) NO2
d) N2O

View Answer

Answer: b [Reason:] The chemiluminescence reactor with ozonator is specific to NO. Here, the sample containing NO is converted into NO2 by the ozonator.

9. In which of the following ways can chemiluminescence occur in compounds of nitrogen?
a) When NO2 returns to ground state from excited state
b) When NO reacts with oxygen
c) When NO reacts with ozone
d) When NO2 is reduced to NO

View Answer

Answer: a [Reason:] When NO2 returns to ground state from excited state, chemiluminescence occurs. NO2 in excited state returns to ground state with the emission of radiant energy.

10. West-Gaeke colorimetric method is used to analyse oxides of nitrogen.
a) True
b) False

View Answer

Answer: b [Reason:] West-Gaeke colorimetric method is not used to analyse oxides of nitrogen. It is used to analyse sulphur di-oxide.

Set 3

1. The function of pressure regulators in emission system of flame photometer is to have a steady flame which is free from flickers.
a) True
b) False

View Answer

Answer: a [Reason:] The function of pressure regulators is to have a steady flame which is free from flickers. Pressure gauges indicate the pressure.

2. In Total consumption burner, only samples of particular droplet size will enter the burner.
a) True
b) False

View Answer

Answer: b [Reason:] Samples will enter the burner irrespective of their droplet size. Hence, it has the name Total consumption burner.

3. Which of the following is the principle of Flame emission photometers?
a) Radiation is absorbed by non-excited atoms in vapour state and are excited to higher states
b) Medium absorbs radiation and transmitted radiation is measured
c) Colour and wavelength of the flame is measured
d) Only wavelength of the flame is measured

View Answer

Answer: c [Reason:] In Flame emission photometers, colour and intensity of the flame is measured. The intensity of light emitted when sample is introduced into the flame is also measured.

4. In Flame emission photometers, the measurement of _____________ is used for qualitative analysis.
a) Colour
b) Intensity
c) Velocity
d) Frequency

View Answer

Answer: a [Reason:] The colour and the wavelength of the flame are used for qualitative analysis. It is used to determine the element which is present in the sample.

5. In Flame emission photometers, the measurement of _____________ is used for quantitative analysis.
a) Colour
b) Intensity
c) Velocity
d) Frequency

View Answer

Answer: b [Reason:] The intensity of the flame is used for quantitative analysis. It is used to determine the amount of element present in the sample.

6. Which of the following is not an advantage of Laminar flow burner used in Flame photometry?
a) Noiseless
b) Stable flame for analysis
c) Efficient atomization of sample
d) Sample containing two or more solvents can be burned efficiently

View Answer

Answer: d [Reason:] Sample containing two or more solvents cannot be burned efficiently in Laminar flow burner. One more advantage of laminar flow burner is that it allows steady movement of gas flow.

7. Laminar flow burner used in Flame photometers is also known as ____________
a) Turbulent burner
b) Premix burner
c) Total consumption burner
d) Nozzle mix burner

View Answer

Answer: b [Reason:] Laminar flow burner used in Flame photometers is also known as Premix burner. Sample, fuel and oxidant are mixed thoroughly before reaching the burner.

8. Which of the following is the advantage of prism monochromators?
a) Dispersion is non-overlapping
b) Dispersion occurs in non-linear manner
c) Dispersion is overlapping
d) Dispersion occurs in a linear manner

View Answer

Answer: a [Reason:] The advantage of prism is that, dispersion that occurs is non-overlapping. The disadvantage is that it occurs in a non-linear manner.

9. Which of the following is the advantage of grating monochromators?
a) Dispersion is non-overlapping
b) Dispersion occurs in non-linear manner
c) Dispersion is overlapping
d) Dispersion occurs in a linear manner

View Answer

Answer: d [Reason:] The advantage of grating is that, dispersion that occurs is linear. The disadvantage is that the dispersion is overlapping.

10. Which of the following is not a detector used in Flame emission photometers?
a) Photronic cell
b) Photovoltaic cell
c) Photoemissive tube
d) Chromatogram

View Answer

Answer: d [Reason:] Detectors used in Flame emission photometers are Photovoltaic cell and photo emissive tubes. Photovoltaic cell is also known as photronic cell.

11. Phototubes are more sensitive than photovoltaic cells.
a) True
b) False

View Answer

Answer: a [Reason:] Phototubes are more sensitive than photovoltaic cells. Therefore, it can be used to measure low intensities.

12. Which of the following is not an application of Flame emission photometers?
a) Analysis of biological fluids
b) Determination of sodium, potassium in soil
c) Determination of metals such as Mn, Cu
d) Analysis of complex mixtures

View Answer

Answer: d [Reason:] The applications of Flame emission photometers are analysis of biological fluids, determination of sodium and potassium in soil and determination of metals such as Mn and Cu. It is also used for the analysis of plant materials and industrial cements.

13. Given below is the diagram of Flame emission photometers. Identify the unmarked component.
analytical-instrumentation-questions-answers-flame-emission-q13
a) Filter
b) Atomiser
c) Pressure regulator
d) Burner

View Answer

Answer: d [Reason:] The unmarked portion is Burner. Burner is where flame is obtained by mixing sample, fuel and oxygen.

14. Given below is the diagram of evacuated glass tube of photo emissive tube. Identify the part which is indicated with a question mark.
analytical-instrumentation-questions-answers-flame-emission-q14
a) Anode
b) Cathode
c) Grid
d) Dynode

View Answer

Answer: b [Reason:] The cathode is formed of half cylinder. The anode is a metal ring near the centre of the glass.

15. Which of the following is not an advantage of photovoltaic cell which is used as a detector in Flame emission photometers?
a) Portable
b) No external supply
c) Robust in construction
d) Does not show fatigue

View Answer

Answer: d [Reason:] It does show fatigue. It shows decrease in response with continued illumination.

Set 4

1. Which of the following is not true about Fourier Transform Infrared (FTIR) spectrometer?
a) It is of non-dispersive type
b) It is useful where repetitive analysis is required
c) Size has been reduced over the years
d) Size has increased over the years

View Answer

Answer: d [Reason:] FTIR is of non-dispersive type of instruments and is used for repetitive analysis. Initially, it was bulky and cost was high and hence, it was limited to special application. Now, the size has been reduced.

2. In the most widely used beam splitter, a thin film of ________ is sandwiched between two plates of low refractive index solid. Fill the blank with the suitable option.
a) Mylar
b) Silicon carbide
c) Ferrous oxide
d) Silver chloride

View Answer

Answer: a [Reason:] Generally, mylar is the thin film used in beam splitters. Beam splitter has to pass 50% of the radiation and reflect 50% of the radiation.

3. Which of the following is not the function of drive mechanism in Fourier Transform Infrared Spectrophotometer?
a) Movement of mirror to obtain a satisfactory interferogram
b) Acquire a good interferogram pattern
c) Allow 50% of the beam to pass
d) Keep the speed of the moving mirror constant

View Answer

Answer: c [Reason:] Drive mechanism does the functions specified in the other options. It the function of the beam splitter to allow 50% of the beam to pass through.

4. Only pyroelectric transducer or pyroelectric crystals are used as detectors in Fourier Transform Infrared Spectrophotometer (FTIR). What is the main reason for other types of thermal detectors are not being used in FTIR spectrophotometer?
a) Less accuracy
b) Slower response
c) Less precision
d) Less sensitivity

View Answer

Answer: b [Reason:] Other thermal detectors are not employed due to slower response of the detectors. Pyroelectric transducers or pyroelectric crystals are chosen for their high speed, accuracy, precision, sensitivity and resolution.

5. Which of the following is not the advantage of Fourier Transform Spectrometers?
a) Signal to noise ratio is high
b) Information could be obtained on all frequencies
c) Retrieval of data is possible
d) Easy to maintain

View Answer

Answer: d [Reason:] The instrument is not easy to maintain and it is a disadvantage. The other disadvantage is that the cost is high.

6. Which of the following has to be computed to determine transmittance and absorbance at various frequencies?
a) Ratio of signal and noise
b) Ratio of sample and reference spectra
c) Sample spectra
d) Reference spectra

View Answer

Answer: b [Reason:] The ratio of sample and reference spectra needs to be computed to determine transmittance and absorbance. First, reference interferogram is obtained and then sample is obtained.

7. Computer accepts analog signals directly.
a) True
b) False

View Answer

Answer: b [Reason:] Computer does not accept analog signals directly. An A/D converter is required to feed the signals to the computer.

8. Which of the following is the reference that is generally used in FTIR interferometer?
a) Air
b) NaCl solution
c) Alcohol
d) Base solution

View Answer

Answer: a [Reason:] Air is generally used as the reference. It is scanned for about 20 to 30 times and the results are stored in a computer.

9. In Michelson Interferometer, if the reflected and transmitted beams are in phase at the beam splitter, then maximum intensity will reach the detector.
a) True
b) False

View Answer

Answer: a [Reason:] If the reflected and transmitted beams are in phase at the beam splitter then maximum intensity will reach the detector. If they are out of phase, then minimum intensity will reach the detector.

10. The diagram given below is the representation of Fourier transform interferometer. Identify the missing block in the block diagram.
analytical-instrumentation-questions-answers-fourier-transform-infrared-spectrometers-q10
a) Pyroelectric crystal
b) Display
c) High speed plotter
d) A/D converter

View Answer

Answer: d [Reason:] Computer does not accept analog signals directly. An A/D converter is required to feed the signals to the computer.

11. In Michelson’s interferometer, the frequency of the detector output can be determined by translating the _________ of movable mirror and the ___________ of monochromatic radiation.
a) Velocity, wavelength
b) Thickness, intensity
c) Length, velocity
d) Angle, intensity

View Answer

Answer: a [Reason:] The frequency can be determined by translating the velocity of the movable mirror and the wavelength of monochromatic radiation. The reflected beam passes towards the movable mirror.

12. In Michelson’s interferometer, the __________ of the detector output will depend upon the intensity of incoming radiation.
a) Velocity
b) Frequency
c) Amplitude
d) Phase

View Answer

Answer: c [Reason:] In Michelson’s interferometer, the amplitude of the detector output will depend upon the intensity of incoming radiation. If movable mirror is moved uniformly, the output will be a sine wave.

13. Why is the computer necessary in Fourier Transform Spectrometer?
a) To display the detector output
b) To process the detector output
c) To determine the amplitude
d) To determine the frequency

View Answer

Answer: b [Reason:] The computer is necessary to process the output of the detector. The Fourier Transform of output is determined using software using computers.

Set 5

1. For the separation of which of the following substances, Gas-solid chromatography is being used?
a) Thermally stable organic components
b) Volatile organic components
c) Thermally stable inorganic components
d) Low molecular weight gaseous species

View Answer

Answer: d [Reason:] Gas-solid chromatography is used for the separation of low molecular weight gaseous species. Its application is limited because of semi-permanent retention of the analyte.

2. Which of the following is not a feature of carrier gas used in gas chromatography?
a) It must be chemically inert
b) It should be suitable for the detector employed
c) It should not be completely pure
d) It should be cheap

View Answer

Answer: c [Reason:] It should be highly pure. Further, it should be readily available and non-inflammable.

3. Which of the following is the disadvantage of hydrogen, which can be used as carrier gas in gas chromatography?
a) Dangerous to use
b) Expensive
c) Reduced sensitivity
d) High density

View Answer

Answer: a [Reason:] Hydrogen is dangerous to use. It has better thermal conductivity and lower density.

4. Which of the following is the disadvantage of helium, which can be used as carrier gas in gas chromatography?
a) Dangerous to use
b) Expensive
c) Reduced sensitivity
d) High density

View Answer

Answer: b [Reason:] Helium is expensive. Its advantages are that it has low density and it allows greater flow rates.

5. Which of the following is the disadvantage of nitrogen, which can be used as carrier gas in gas chromatography?
a) Dangerous to use
b) Expensive
c) Reduced sensitivity
d) High density

View Answer

Answer: c [Reason:] Nitrogen has reduced sensitivity. It is still one of the commonly used carrier gas in gas chromatography.

6. Slow injection of large samples leads to band broadening and loss of resolution.
a) True
b) False

View Answer

Answer: Slow injection of large samples leads to band broadening and loss of resolution. Hence, for desired column efficiency, samples should not be too large.

7. In which of the following methods are liquid samples injected into the column in gas chromatography?
a) Gas tight syringe
b) Micro-syringe
c) Rotary sample valve
d) Solid injection syringes

View Answer

Answer: b [Reason:] Liquid samples injected into the column in gas chromatography using micro-syringe. Syringes of various capacities are available.

8. What must be done to the solid samples for it to be introduced into the column without using solid injection syringes in gas chromatography?
a) Introduced in hot-zone of the column
b) Dissolved in volatile liquids
c) Introduced using rotary sample valve
d) Introduced using sampling loops

View Answer

Answer: b [Reason:] Solid samples must be dissolved in volatile liquids for introducing it into the column. They can be introduced directly using solid injection syringes.

9. Which of the following is the commonly used support material for the packed column in gas chromatography?
a) Glass
b) Metal
c) Diatomaceous earth
d) Stainless steel

View Answer

Answer: c [Reason:] Diatomaceous earth is the commonly used support material for the packed column in gas chromatography. The columns could be made of glass or metal.

10. Which of the following is the advantage of straight packed column?
a) It can be packed uniformly
b) It can be repacked easily
c) It is compact
d) It is easier to heat it evenly

View Answer

Answer: c [Reason:] The advantage of straight column is that it can be repacked easily. It is not compact in size.

11. Which of the following is the disadvantage of coiled or helical shaped packed chromatographic column?
a) It cannot be packed uniformly
b) It cannot be repacked easily
c) It is not compact
d) It is not easy to heat it evenly

View Answer

Answer: b [Reason:] The disadvantage of coiled or helical shaped packed chromatographic column is that it cannot be repacked easily. It is compact in size and can easily be heated in an even manner.

12. Capillary columns are open tubular columns constructed from which of the following materials?
a) Glass
b) Metal
c) Stainless steel
d) Fused silica

View Answer

Answer: d [Reason:] Capillary columns are constructed using fused silica. It is a very high purity glass.

13. Sample injection port must be maintained at a temperature at which rapid vapourisation occurs but thermal degradation does not occur.
a) True
b) False

View Answer

Answer: a [Reason:] Sample injection port must be maintained at a temperature at which rapid vapourisation occurs but thermal degradation does not occur. The column is maintained at a different temperature.

14. Which of the following is not a desirable feature of the ovens used in gas chromatography?
a) It must have a fast rate of heating
b) Power consumption should be kept low
c) It must have maximum thermal gradients
d) It should have proper insulation

View Answer

Answer: c [Reason:] The ovens used in gas chromatography must have maximum thermal gradients. The temperature must be uniform over the whole column.

15. Given below is the block diagram of gas chromatography. Identify the unmarked component.
analytical-instrumentation-questions-answers-gas-chromatography-q15
a) Pumping system
b) Pressure regulator
c) Flow regulator
d) Sample injection system

View Answer

Answer: d [Reason:] The unmarked component is syringe. Hence, the answer is sample injection system. It is for the introduction of sample into the flowing gas stream.

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