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Multiple choice question for engineering

Set 1

1. Which is the missing block in the block diagram for Absorption of Radiation Instrument given below?
analytical-instrumentation-questions-answers-absorption-instrumentation-q1
a) Filter
b) Reflector
c) Converging lens
d) Detector

View Answer

Answer: d [Reason:] To measure the amount of radiation absorbed and transmitted detector is very important. It detects the amount of radiation which is then inferred using read out device.

2. Which of the following detectors does not require a battery and is also known as barrier layer cell?
a) Photomultiplier tube
b) Photovoltaic cell
c) Photoemissive tubes
d) Photo reflector

View Answer

Answer: b [Reason:] Photovoltaic cell does not require a battery for operation. Its working is entirely different from Photomultiplier tube or Photoemissive tubes.

3. Which of the following detectors is used to detect light intensities which are very weak?
a) Photomultiplier tube
b) Photovoltaic cell
c) Photoemissive tubes
d) Photo reflector

View Answer

Answer: a [Reason:] PMT is used for detection of light intensities which are weak. As the name suggests, Photomultiplier tube multiplies the incident electrons using dynodes causing an avalanche of electrons.

4. How is Tungsten Halogen lamp differ from normal Tungsten filament lamp used in absorption spectroscopy?
a) It has a tungsten filament and is filled with inert gas
b) Iodine is added to normal filling gas
c) Iodine is coated on tungsten filament
d) Iodine is added to inert gas

View Answer

Answer: b [Reason:] In Tungsten filament lamp tungsten filament is enclosed in a bulb of glass filled with inert gas or vacuum. In Tungsten Halogen lamp iodine is added to normal filling glass.

5. Instead of glass filters, why gelatin filters could not be used for a long period while both are Absorption filters?
a) Gelatin tends to evaporate and hence they deteriorate
b) Gelatin is affected by humidity in environment
c) They deteriorate due to absorption of heat leading to changes in gelatin
d) Gelation is affected by temperature in environment

View Answer

Answer: c [Reason:] With absorption of heat they deteriorate due to changes in gelatin. Bleaching of dye occurs.

6. How does continuous wedge filter differ from normal interference filter used in absorption spectroscopy?
a) It permits continuous selection of different wavelength
b) It allows narrow band of wavelengths to pass
c) It has two semi-transparent layers of silver
d) Space layer is made of a substance having low refractive index

View Answer

Answer: a [Reason:] It allows continuous selection of wavelength by using a spacer film of graded thickness. Rest of the options are properties of normal interference filters.

7. Which of the following could be used as the layer of dielectric in interference filters used in Absorption Spectroscopy?
a) Graphite
b) MgF2
c) Fe
d) AgNO3

View Answer

Answer: b [Reason:] MgF2 is used as layer of dielectric in interference filters. Other material that can be used is ZnS.

8. How can stability of radiation be achieved in incandescent or discharge source used in Absorption Spectroscopy?
a) Using filters
b) Using monochromators
c) Using slits
d) By controlling the source voltage

View Answer

Answer: d [Reason:] The intensity of radiation in incandescent source is proportional to the lamp source voltage. Therefore, by controlling the source voltage stability can be achieved.

9. To tolerate high operating temperatures, which of the following has to be done in incandescent or tungsten filament lamps?
a) Alloys must be used
b) Nitrogen be used instead of inert gas
c) Envelope is fabricated with quartz
d) Envelope is fabricated with copper

View Answer

Answer: c [Reason:] The envelope is fabricated with quartz to allow high operating temperatures. Tungsten filament and inert gas are generally used and are not modified.

10. Which of the following is not a reason for laser not being generally used as a source of radiation for UV, Visible Spectroscopy?
a) High cost
b) Limited range of wavelength
c) Less intensity
d) Complex to work with

View Answer

Answer: c [Reason:] Laser has high intensity. It is used in special applications where cost is not a matter and limited range of wavelength is required.

Set 2

1. What is the drawback that occurs in using ion exchange chromatography on sulphonated polystyrene resin and colourimetry for amino-acid analysis?
a) Less accuracy
b) Low resolution
c) Inconvenient to handle many individual samples
d) Slow in operation

View Answer

Answer: c [Reason:] When ion exchange chromatography is used for amino-acid analysis, high accuracy is obtained. It is inconvenient to handle many individual samples and cleaning of glassware is laborious.

2. Which one of the following methods is the most suitable for amino-acid analysis?
a) Gas chromatography
b) Ion exchange chromatography
c) Paper electrophoresis
d) Resin column chromatography

View Answer

Answer: d [Reason:] Resin column chromatography is the most suitable for amino-acid analysis. Here, ion exchange resin chromatography is followed.

3. Which of the following colour reagents are used in Resin column chromatography?
a) Marquis reagent
b) Benedict reagent
c) Ninhydrin
d) Nessler’s reagent

View Answer

Answer: d [Reason:] Ninhydrin is the colour reagent used in resin column chromatography. The colour reaction occurs during a known period and controlled temperature.

4. Which of the following amino-acids is measured at a wavelength of 440nm using photometric systems?
a) Proline
b) Alanine
c) Glutamine
d) Valine

View Answer

Answer: a [Reason:] Proline and hydroxyproline are measured at 440nm. All the other amino-acids are measured at 570nm.

5. In Automatic amino-acid analyzer, the sample containing ___________ of each amino compound is introduced at the top of the ion exchange column.
a) 1 to 10 µmoles
b) 1 to 10 moles
c) 0.05 to 2 moles
d) 0.05 to 2 µmoles

View Answer

Answer: d [Reason:] In Automatic amino-acid analyzer, the sample having 0.05 to 2 µmoles of each amino compound is introduced at the top of the ion exchange column. Buffer is then supplied to the column.

6. Which of the following cannot be analysed using resin column chromatography?
a) Peptides
b) Amines
c) Amino compounds
d) Components which are ninhydrin negative

View Answer

Answer: d [Reason:] Components which are ninhydrin negative cannot be analysed using resin column chromatography. Only the components that are nindydrin positive are analysed using this method.

7. Trapped air in pumps of Automatic amino-acid analyzer is eliminated using which of the following ways?
a) Suction pump
b) De-aerator
c) Overcome naturally by pump pressure
d) Using pulse damper

View Answer

Answer: b [Reason:] De-aerator is used to eliminate trapper air in pumps of automatic amino-acid analyzer. Here, bubble-trap type de-aerator is used.

8. Amino-acids are distinguishable from each other only by one or two atoms in their structure.
a) True
b) False

View Answer

Answer: a [Reason:] Amino-acids are distinguishable from each other only by one or two atoms in their structure. They are components all proteins and are essential for growth of organisms.

9. What is the drawback that occurs in using gas chromatography for amino-acid analysis?
a) Costly
b) Cannot be used for proteins or polypeptides
c) Slow process
d) Complex in operation

View Answer

Answer: b [Reason:] Gas chromatography cannot be used for proteins or polypeptides. Further, accuracy is lost while converting amino-acids into gaseous phase.

10. Resin column chromatography does not involve breaking of bonds in amino-acids.
a) True
b) False

View Answer

Answer: b [Reason:] Resin column chromatography involves breaking of bonds in amino-acids. This causes a delay as acid is eluted through the column by a buffer.

Set 3

1. Which of the following is the relationship between density of ideal gas and its molecular weight?
a) Directly proportional
b) Inversely proportional
c) Linear
d) No relation

View Answer

Answer: c [Reason:] Density of an ideal gas has a direct linear relation with the molecular weight of the gas.Density can be used to analyse gases.

2. Under which of the following conditions do all real gases behave as ideal gases to some extent?
a) Low temperature and low pressure
b) Low temperature and high pressure
c) High temperature and low pressure
d) Room temperature and normal pressure

View Answer

Answer: d [Reason:] All real gases behave as ideal gases at room temperature and normal pressure. Hence, density can be used to analyse gases.

3. Which of the following detectors are not used in analyzers based on gas density?
a) Hot wire
b) Platinum filament
c) Thermistor
d) Thermometer

View Answer

Answer: d [Reason:] Thermometer is not used as detector in analyzers based on gas density. Thermistors and hot wires are generally used.

4. When would the recorder indicate a zero base line in analyzers based on gas density?
a) When the detector on the sample side is cooler than that on the reference side
b) When the detector on the reference side is cooler than that on the sample side
c) When flow is unbalanced
d) When both the detectors are equally cooled

View Answer

Answer: d [Reason:] The recorder indicates a zero base line in analyzers based on gas density when flow is balanced. When flow is balanced both the detectors are equally cooled.

5. The use of thermistor eliminates the requirement for amplification.
a) True
b) False

View Answer

Answer: a [Reason:] The use of thermistor eliminates the requirement for amplification. Hence, it is generally used in analyzers based on gas density.

6. In analyzers based on gas density, the unbalance of the bridge is linearly proportional to which of the following?
a) Temperature of sample detector
b) Pressure at sample detector
c) Pressure difference between both the detectors
d) Gas-density difference between both the detectors

View Answer

Answer: d [Reason:] In analyzers based on gas density, the unbalance of the bridge is linearly proportional to gas-density difference between both the detectors. Instruments based on principle of gas-density balance are commercially available.

7. Which of the following bridges are used in analyzers based on gas density?
a) Wheatstone bridge
b) Kelvin’s bridge
c) Anderson’s bridge
d) Schering’s bridge

View Answer

Answer: a [Reason:] Wheatstone bridge is generally used in analyzers based on gas density. Themistors or hot-wires can be used as detectors.

8. In analyzers based on gas density, if the sample carries a gas having higher density than the detector which of the following occurs?
a) It will cause a net downward flow
b) It will cause a net upward flow
c) It splits into two beams
d) There will be no difference in flow

View Answer

Answer: a [Reason:] In analyzers based on gas density, if the sample carries a gas having higher density than the detector it will cause a net downward flow. It will obstruct flow in the lower path.

9. When hot-wires are used as detectors amplification is not required.
a) True
b) False

View Answer

Answer: b [Reason:] When hot-wires are used as detectors amplification is required. The amplified signal is given to the recorder.

10. Which of the following is the effective sample volume in analyzers based on gas density?
a) 10 ml
b) 20 ml
c) 5 ml
d) 50 ml

View Answer

Answer: c [Reason:] The effective sample volume in analyzers based on gas density is 5ml. Instruments based on principle of gas-density balance are commercially available.

Set 4

1. Which of the following is the principle of Atomic Absorption Spectroscopy?
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 is measured
d) Colour is simply observed

View Answer

Answer: a [Reason:] Atoms in gaseous state absorb the radiation and are excited to higher state. Since, the higher state is unstable the atom returns the ground state with the emission of radiation which is measured.

2. In Atomic Absorption Spectroscopy, which of the following is the generally used radiation source?
a) Tungsten lamp
b) Xenon mercury arc lamp
c) Hydrogen or deuterium discharge lamp
d) Hollow cathode lamp

View Answer

Answer: d [Reason:] Hollow cathode lamp is the source used in Atomic Absorption Spectroscopy. It emits stable and intense radiation.

3. In Atomic Absorption Spectroscopy, with what material is the cathode in Hollow cathode lamp constructed?
a) Tungsten
b) Quartz
c) Element to be investigated
d) Aluminium

View Answer

Answer: c [Reason:] The cathode in Hollow cathode lamp is constructed of the element to be investigated. The anode is made of tungsten.

4. How can the intensity of radiation be increased in Hollow cathode lamp?
a) Addition of non-conductive protective shield of mica
b) Addition of nitrogen to neon or argon in the lamp
c) Increasing the pressure of the filling gas
d) Changing the metal of the anode

View Answer

Answer: a [Reason:] The intensity of radiation is increased in Hollow cathode lamp by the addition of non-conductive protective shield of mica. The protective shield can be made of glass too.

5. Which of the following is the function of the chopper in Atomic Absorption Spectroscopy?
a) To split the beam into two
b) To break the steady light into pulsating light
c) To filter unwanted components
d) To reduce the sample into atomic state

View Answer

Answer: b [Reason:] The function of the chopper in Atomic Absorption Spectroscopy is to break the steady light into pulsating light. It is a rotating wheel placed between the flame and the source.

6. Which of the following is the function of Flame or Emission system in Atomic Absorption Spectroscopy?
a) To split the beam into two
b) To break the steady light into pulsating light
c) To filter unwanted components
d) To reduce the sample into atomic state

View Answer

Answer: d [Reason:] The function of Flame or Emission system in Atomic Absorption Spectroscopy is to reduce the sample into atomic state. In Atomic Absorption Spectroscopy, the production of atomic vapour by flame is the most important phase.

7. Atomic absorption spectroscopy is also called as Absorption Flame Photometry.
a) True
b) False

View Answer

Answer: a [Reason:] In Atomic Absorption Spectroscopy, sample is sprayed into the flame. Hence, it is called Absorption Flame Photometry.

8. Which of the following is not a component of emission system in Flame photometer?
a) Burner
b) Atomiser
c) Fuel gases and their regulation
d) Chopper

View Answer

Answer: d [Reason:] Chopper is not a component of emission system in Flame photometer. The parts of flame photometer are burner, atomiser, fuel gases and their regulation and flame.

9. Which of the following is the function of atomiser in the emission system of Atomic Absorption Spectroscopy?
a) To split the beam into two
b) To break the steady light into pulsating light
c) To break large mass of liquid into small drops
d) To reduce the sample into atomic state

View Answer

Answer: c [Reason:] The function of atomiser in the emission system of Atomic Absorption Spectroscopy is to break large mass of liquid into small drops. It also introduces liquid sample into the flame at a stable rate.

10. Which of the following is not a fuel used in flame photometry?
a) Acetylene
b) Propane
c) Hydrogen
d) Camphor oil

View Answer

Answer: d [Reason:] The commonly used fuel gases in flame photometry are acetylene, propane and hydrogen. Oxygen supply is given to the fuel gases.

11. Which of the following is not the requirement of a good flame in flame photometer?
a) Liquid sample must be evaporated to form solid residue
b) Solid residue must decompose to form atoms
c) Atoms must be produced such that they have the ability to get excited to higher states
d) Atoms must be produced such that they are in stable state

View Answer

Answer: d [Reason:] Atoms must be produced such that they have the ability to get excited to higher states. These atoms in higher states return to ground state with the emission of photons.

12. Atomic Absorption Spectroscopy is used for the analysis of metals.
a) True
b) False

View Answer

Answer: a [Reason:] Atomic Absorption Spectroscopy is used for the analysis of metals.

13. Which of the following options explains the process of ‘sputtering’ that occurs in Hollow Cathode Lamp?
a) Positive ions collide with cathode surface and metal atoms from cathode are ejected
b) Negative ions collide with cathode surface and metal atoms from anode are ejected
c) Positive ions collide with negative ions and metal atoms from anode are ejected
d) Positive ions collide with negative ions and photons are ejected

View Answer

Answer: a [Reason:] When potential is applied across the electrode, the gas filled in tube ionises and flow of current occurs. Positive ions collide with negatively charged cathode surface and metal atoms from cathode are ejected.

14. At what pressure should the gases in the sealed tube be maintained in the Hollow cathode lamp?
a) 1 to 5 torr
b) 20 to 30 torr
c) 40 to 50 torr
d) 50 to 55 torr

View Answer

Answer: a [Reason:] It consists of a cylindrical cathode and an anode made of tungsten. The tube is sealed and neon and argon are filled at a pressure of 1 to 5 torr.

15. The diagram show below is the picture of Hollow cathode lamp. Identify the unmarked component.
analytical-instrumentation-questions-answers-atomic-absorption-q15
a) Glass tube
b) Quartz window
c) Non- conducting glass
d) Mica shield

View Answer

Answer: b [Reason:] The unmarked portion is Quartz window. The window can be made of quartz or borosilicate glass.

Set 5

1. How is molar concentration of solute in stationary phase related to molar concentration of solute in mobile phase?
a) Directly proportional
b) Inversely proportional
c) Equal
d) Not related

View Answer

Answer: a [Reason:] 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.

2. If the value of the distribution constant ‘k’ is one, then what could be inferred about the distribution of solute?
a) Its distribution in stationary phase is greater
b) Its distribution in mobile phase is greater
c) It is equally distributed in stationary and mobile phase
d) It is distributed in a random manner

View Answer

Answer: c [Reason:] Cs α Cm Cs = k Cm If k=1, it denotes that the solute is equally distributed in mobile and stationary phase.

3. The time taken by the analyte after sample injection to reach the detector is called _________
a) Dead time
b) Solute migration rate
c) Adjusted retention time
d) Retention time

View Answer

Answer: d [Reason:] 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.

4. The time required for a molecule of the mobile phase to pass through the column is called ___________
a) Dead time
b) Solute migration rate
c) Adjusted retention time
d) Retention time

View Answer

Answer: a [Reason:] 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.

5. Adjusted retention time is the remaining retention time after subtracting __________ from ___________
a) Solute migration rate and retention time
b) Retention time and solute migration rate
c) Dead time and retention time
d) Retention time and dead time

View Answer

Answer: c [Reason:] Adjusted retention time is the remaining retention time after subtracting dead time from retention time. It affects the effectiveness of the system.

6. Which of the following is the volume of mobile phase required to make a solute band move from the point of injection through the column to the detector?
a) Dead volume
b) Retention volume
c) Void volume
d) Adjusted retention volume

View Answer

Answer: b [Reason:] 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.

7. Adjusted retention volume is the remaining retention volume after subtracting ___________ from _____________
a) Solute migration rate and retention volume
b) Retention volume and solute migration rate
c) Dead volume and retention volume
d) Retention volume and dead volume

View Answer

Answer: c [Reason:] Adjusted retention volume is the remaining retention volume after subtracting dead volume from retention volume. Vadjusted retention = Vretention – Vdead

8. Which of the following is defined as the ratio of moles of solute in stationary phase to the moles of solute in mobile phase?
a) Distribution constant
b) Volumetric phase ratio
c) Retention factor
d) Total porosity

View Answer

Answer: c [Reason:] Retention factor is defined as the ratio of moles of solute in stationary phase to the moles of solute in mobile phase. It is used for determining the migration rates of solutes in the column.

9. Which of the following is the ratio of interstitial volume of packing to the volume of its total mass?
a) Distribution constant
b) Volumetric phase ratio
c) Retention factor
d) Total porosity

View Answer

Answer: d [Reason:] Total porosity is the ratio of interstitial volume of packing to the volume of its total mass. In capillary column, total porosity is 1.

10. Which of the following is the ratio of length of column packing to dead time?
a) Average linear rate of solute migration
b) Average linear rate of mobile migration
c) Relative migration rate
d) Selectivity factor

View Answer

Answer: b [Reason:] Average linear rate of mobile migration is the ratio of length of column packing to dead time. It influences the effectiveness of the column in separating solutes.

11. Which of the following is the ratio of length of column packing to retention time?
a) Average linear rate of solute migration
b) Average linear rate of mobile migration
c) Relative migration rate
d) Selectivity factor

View Answer

Answer: a [Reason:] Average linear rate of solute migration is the ratio of length of column packing to retention time. It influences the effectiveness of the column in separating solutes.

12. Retention distance is the distance between point of injection and minimum peak in the recorder or computer generated chart.
a) True
b) False

View Answer

Answer: b [Reason:] Retention distance is the distance between point of injection and maximum peak in the recorder. The chart is drawn between time and concentration of the solute.

13. Retention volume can be obtained by finding the product of which of the following parameters?
a) Dead time and total porosity
b) Retention time and volumetric flow rate
c) Adjusted retention time and volumetric flow rate
d) Retention time and total porosity.

View Answer

Answer: b [Reason:] Retention volume can be obtained by finding the product of retention time and volumetric flow rate. Flow rate = Cross section of empty column × Average linear velocity × Total porosity

14. Retention factor is also known as capacitance factor.
a) True
b) False

View Answer

Answer: a [Reason:] Retention factor is also known as capacitance factor. It can be denoted as k’.

15. What must be the value of selectivity factor?
a) Equal to 1
b) Less than 1
c) Greater than 1
d) Greater than 0

View Answer

Answer: c [Reason:] Selectivity factor/ Relative retention must always be greater than 1. It is also known as Relative migration rate.

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