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# Multiple choice question for engineering

## Set 1

1. Beer Lambert’s law gives the relation between which of the following?
a) Reflected radiation and concentration
b) Scattered radiation and concentration
c) Energy absorption and concentration
d) Energy absorption and reflected radiation

Answer: c [Reason:] Beer Lambert’s law give the relation between Energy absorption and Concentration. It was proposed by Beer and Lambert.

2. In which of the following ways, absorption is related to transmittance?
a) Absorption is the logarithm of transmittance
b) Absorption is the reciprocal of transmittance
c) Absorption is the negative logarithm of transmittance
d) Absorption is a multiple of transmittance

Answer: c [Reason:] Transmittance is the ratio of the radiant power transmitted by a sample to the radiant power incident on the sample. Absorption is the negative logarithm of transmittance.

3. Which of the following is not a limitation of Beer Lambert’s law, which gives the relation between absorption, thickness and concentration?
a) Concentration must be lower
b) Radiation must have higher bandwidth
c) Radiation source must be monochromatic
d) Does not consider factors other than thickness and concentration that affect absorbance

Answer: b [Reason:] The law is derived assuming that the radiation is monochromatic. So, if bandwidth increases it will create deviation.

4. Beer’s law states that the intensity of light decreases with respect to ___________
a) Concentration
b) Distance
c) Composition
d) Volume

Answer: a [Reason:] Beer’s law states that the intensity of light decreases with the concentration of the medium. It was stated by Beer.

5. Lambert’s law states that the intensity of light decreases with respect to __________
a) Concentration
b) Distance
c) Composition
d) Volume

Answer: b [Reason:] Lambert’s law states that the intensity of light decreases with respect to concentration of the medium. It was stated by Lambert.

6. The representation of Beer Lambert’s law is given as A = abc. If ‘b’ represents distance, ‘c’ represents concentration and ‘A’ represents absorption, what does ‘a’ represent?
a) Intensity
b) Transmittance
c) Absorptivity

Answer: c [Reason:] ‘a’ represents the absorption constant. It is also known as absorptivity.

7. Which of the following is not true about Absorption spectroscopy?
a) It involves transmission
b) Scattering is kept minimum
c) Reflection is kept maximum
d) Intensity of radiation leaving the substance is an indication of concentration

Answer: c [Reason:] In Absorption spectroscopy, reflection must also be kept minimum along with scattering. Amount of absorption depends on the number of molecules in the material.

8. Transmittance is given as T = P/Po. If Po is the power incident on the sample, what does P represent?
a) Radiant power transmitted by the sample
b) Radiant power absorbed by the sample
c) Sum of powers absorbed and scattered
d) Sum of powers transmitted and reflected

Answer: a [Reason:] P represents radiant power transmitted by the sample. Transmittance is the ratio of radiant power transmitted by the sample to the radiant power that is incident on it.

9. What is the unit of absorbance which can be derived from Beer Lambert’s law?
a) L mol-1 cm-1
b) L gm-1 cm-1
c) Cm
d) No unit

Answer: d [Reason:] Absorbance has no unit. The units of absorptivity, distance and concentration cancel each other. Hence, absorption has no unit.

10. What is the unit of molar absorptivity or absorptivity which is used to determine absorbance A in Beer Lambert’s formula?
a) L mol-1 cm-1
b) L gm-1 cm-1
c) Cm
d) No unit

Answer: a [Reason:] The unit of absorptivity is L mol-1 cm-1. If concentration is represented as gm per litre it becomes L gm-1 cm-1.

## Set 2

1. Mass spectrometers are used to determine which of the following?
a) Composition in sample
b) Concentration of elements in sample
c) Relative mass of atoms
d) Properties of sample

Answer: Mass spectrometers are used to determine the relative mass of atoms and molecules. Aston made the instrument more accurate.

2. Who invented mass spectrometers?
a) J.J Thompson
b) Goldstein
c) Nikola Tesla
d) Aston

Answer: a [Reason:] J.J Thompson introduced mass spectrometers. Aston modified the instrument to make it more accurate.

3. In mass spectrometer, the sample that has to be analysed is bombarded with which of the
following?
a) Protons
b) Electrons
c) Neutrons
d) Alpha particles

Answer: b [Reason:] In mass spectrometer, the sample which is to be analysed is bombarded with electrons. As a result, ions are produced.

4. Mass spectrometer separates ions on the basis of which of the following?
a) Mass
b) Charge
c) Molecular weight
d) Mass to charge ratio

Answer: d [Reason:] Mass spectrometer separates ions on the basis of mass to charge ratio. Most of the ions are singly charged. Hence, the mass to charge ratio is equal to the mass.

5. In mass spectrometer, the ions are sorted out in which of the following ways?
a) By accelerating them through electric field
b) By accelerating them through magnetic field
c) By accelerating them through electric and magnetic field
d) By applying a high voltage

Answer: c [Reason:] In mass spectrometer, the ions are sorted out by accelerating them through electric and magnetic field. A record of number of different kinds of ions is called mass spectrum.

6. No two molecules will be fragmented and ionized in exactly the same manner.
a) True
b) False

Answer: a [Reason:] No two molecules will be fragmented and ionized in exactly the same manner. This is how different molecules are identified in a complex mixture.

7. The procedure for mass spectroscopy starts with which of the following processes?
a) The sample is bombarded by electron beam
b) The ions are separated by passing them into electric and magnetic field
c) The sample is converted into gaseous state
d) The ions are detected

Answer: c [Reason:] The procedure for mass spectroscopy starts with converting the sample into gaseous state. This is done by chemical processes.

8. In mass spectrometer, the ion currents are measured using which of the following?
a) Scintillation counter
b) Ion counter
c) Electrometer tube
d) Electric fields

Answer: c [Reason:] The ion currents are measured using sensitive electrometer tube. The ions reaching the collecting plate are measured.

9. Which of the following ions pass through the slit and reach the collecting plate?
a) Negative ions of all masses
b) Positive ions of all masses
c) Negative ions of specific mass
d) Positive ions of specific mass

Answer: d [Reason:] Positive ions of specific mass pass through the slit and reach the collecting plate. These ions are measured.

10. Which of the following statements is not true about mass spectrometry?
a) Impurities of masses different from the one being analysed interferes with the result
b) It has great sensitivity
c) It is suitable for data storage
d) It is suitable for library retrival

Answer: a [Reason:] Impurities of masses different from the one being analysed does not interfere with the result in mass spectroscopy. This is a major advantage of this technique.

11. In mass spectrometer, the sample gas is introduced into the highly evacuated spectrometer tube and it is ionised by electron beam.
a) True
b) False

Answer: a [Reason:] The sample gas is introduced into the highly evacuated spectrometer tube and it is ionised by electron beam. The sample has to be in gaseous state.

## Set 3

1. Which of the following is not a component of the time of flight analyser spectrometer?
a) Ion source
b) Field free separation region
c) Electron multiplication region
d) Photo tube

Answer: d [Reason:] Phototube is not a component of time of flight mass spectrometer. Time of flight mass analyser is a type of mass spectrometer.

2. Time of flight mass spectrometer has unlimited mass range.
a) True
b) False

Answer: a [Reason:] Time of flight mass spectrometer is a type of mass spectrometer. It has unlimited mass range.

3. Which of the following is not an advantage of mass spectrometer?
a) Simple
b) Rugged
c) High sensitivity
d) Unlimited mass range

Answer: c [Reason:] Time of flight mass spectrometers have limited sensitivity and resolution. They are simple and rugged.

4. All the ions entering the tube have the same kinetic energy.
a) True
b) False

Answer: a [Reason:] Separation of ions occurs while they are moving from the ion source to the detector. All the ions entering the tube have the same kinetic energy.

5. If all the ions have the same kinetic energy how are their masses related to their velocities?
a) Mass and velocity are equal
b) Mass and velocity are not related
c) Mass and velocity are directly proportional
d) Mass and velocity are inversely proportional

Answer: d [Reason:] If all the ions have the same kinetic energy, mass and velocity are inversely proportional. This is used in separation of ions.

6. Which of the following is true about time of flight analyser spectrometers?
a) Lighter particles arrive at the detector earlier
b) Heavier particle arrive at the detector earlier
c) Lighter and heavier particles arrive together at the detector
d) Lighter particles do not reach the detector

Answer: a [Reason:] Lighter particles arrive at the detector earlier than the heavier particles. The time difference is used to separate the electrons according to their mass.

7. In time of flight mass spectrometer, ions are formed by which of the following methods?
a) Pulsed ionization method
b) Acceleration method
c) Dynamic method
d) Ion excitation method

Answer: a [Reason:] In time of flight mass spectrometer, ions are formed by pulsed ionisation method. It is a type of mass spectrometer.

8. The evacuated tube is also known as which of the following?
a) Pulse tube
b) Detector tube
c) Drift tube
d) Acceleration tube

Answer: c [Reason:] The evacuated tube is also known as drift tube. The electrons move from source to detector through the tube.

9. The current produced by ions arriving at the collector necessitates the use of which of the following?
a) Wide band amplifier
b) Narrow band amplifier
c) Wide band filter
d) Narrow band filter

Answer: a [Reason:] The current produced by ions arriving at the collector has very short duration.Hence, it necessitates the use of wide band amplifier.

10. Which of the following is an ion optic device in which ions pass through a mirror and their flight is reversed?
a) Reversal device
b) Reflectron
c) Mirror arrangement
d) Separation chamber

Answer: b [Reason:] Reflectron is an ion optic device in which ions pass through a mirror and their flight is reversed. It is used in time of flight mass spectrometer.

11. Which of the following statements about mass spectrometers are not true?
a) Time of flight mass spectrometer has the ability to record entire mass spectrum at a time
b) Time of flight mass spectrometers have poor resolution
c) Conventional spectrometer detects only one peak at a time
d) All spectrometers have the ability to record entire mass spectrum at a time

Answer: d [Reason:] Conventional spectrometer detects only one peak at a time. Time of flight mass spectrometer has the ability to record entire mass spectrum at a time.

## Set 4

1. Which of the following is the most widely employed logic family?
a) Emitter-coupled logic
b) Transistor-transistor logic
c) CMOS logic family
d) NMOS logic

Answer: b [Reason:] Transistor-transistor logic is the most widely employed logic family. It is the most popular logic family.

2. The basic function of TTL gate is which of the following functions?
a) AND
b) OR
c) NOR
d) NAND

Answer: d [Reason:] The basic function of TTL gate is NAND function. It is the most popular logic family.

3. In TTL logic, the input transistor has a number of ________ equal to the desired fan-in of the circuit.
a) Base
b) Collect
c) Emitter
d) Gate

Answer: c [Reason:] In TTL logic, the input transistor has a number of emitter equal to the desired fan-in of the circuit. This is a major advantage.

4. Which of the following is the propagation delay of TTL circuits?
a) 1 s
b) 1 ms
c) 1 ns
d) 1 ps

Answer: c [Reason:] The propagation delay of TTL circuit is 1 ns. It is a main characteristic of TTL circuit.

5. The standard TTL gates are marketed as _______ series.
a) 80
b) 82
c) 74
d) 08

Answer: c [Reason:] The standard TTL gates are marketed as 74 series. They can operate up to 700C.

6. Schottky TTL logic family does not have which of the following features?
a) Good fan-in
b) Good fan-out
c) High speed capability
d) High propagation delay

Answer: d [Reason:] Schottky TTL circuits have reduced propagation delay than normal TTL circuits. The propagation delay of 10ns is very high for some applications.

7. The logic ‘0’ of ECL is represented as ______V and logic ‘1’ is represented as ______V.
a) 1, 1.65
b) 0.9, 1.75
c) 1.2, 2.35
d) 1.9, 4.3

Answer: b [Reason:] The logic ‘0’ of ECL is represented as 0.9 V and logic ‘1’ is represented as 1.75 V. ECL stands for emitter-coupled logic.

8. ECL is a way of achieving higher speed of gate.
a) True
b) False

Answer: a [Reason:] We can achieve high speed of gate by sing ECL. ECL stands for emitter-coupled logic.

9. Which of the following is not the advantage of MOS gates?
a) Low power dissipation
b) Small size
c) Good immunity to noise
d) High switching speeds

Answer: d [Reason:] MOS gates do not have high switching speed. They have limited switching capability.

10. CMOS gates are commercially available as which of the following series?
a) 1000
b) 2000
c) 3000
d) 4000

Answer: d [Reason:] CMOS gates are commercially available as 4000 series. This technique is most suitable for commercial circuits.

11. The switching of MOS gates can be improved by using CMOS.
a) True
b) False

Answer: a [Reason:] The switching of MOS gates can be improved by using CMOS. CMOS stands for complementary MOS. It is an inverter.

## Set 5

1. Gases emit radiation under which of the following conditions which can be used for determination of gases?
a) When mixed with other gases
b) When kept at suitable temperature
c) With sufficient electrical excitation and at suitable pressures
d) When exposed to radiation

Answer: c [Reason:] Gases emit radiation with sufficient electrical excitation and at suitable pressures. Gases emit radiation in different ways. It can be in the form of spark, arc or glow discharge in different parts of radiation spectrum.

2. Which of the following measuring technique is utilized for measuring nitrogen?
a) By using a method based on gas density
b) By using paramagnetic analyzers
c) By using magnetic wind instruments
d) By using a photospectrometer where a gas sample is analysed and detected with a photocell

Answer: d [Reason:] By using a photospectrometer gas sample is analysed, for measuring nitrogen. It is then selectively filtered by using a photocell which provides an appropriate electric signal.

3. The characteristic emission of which colour, when discharge takes place in a low pressure chamber containing gas sample, will indicate the presence of nitrogen while using photospectrometer?
a) Purple
b) Blue
c) Pink
d) Green

Answer: a [Reason:] The characteristic emission of purple colour, when discharge takes place in a low pressure chamber containing gas sample, will indicate the presence of nitrogen while using photospectrometer. These are usually employed in medical applications.

4. Sample rates of nitrogen meter can be adjusted by doing which of the following?
a) By modifying the amplifier
b) With the help of the needle valve
c) By modifying the detector
d) By changing chopper frequency

Answer: b [Reason:] Sample rates of nitrogen meter can be adjusted with the help of needle valve. Modern nitrogen analyzers have digital displays.

5. Which of the following is the normal sampling rate used in nitrogen meters?
a) 13 ml/min
b) 33 ml/min
c) 3 ml/min
d) 43 ml/min

Answer: c [Reason:] The normal sampling rate used in nitrogen meters is 3 ml/min. Modern nitrogen analyzers have digital displays.

6. Nitrogen meters are calibrated for which of the following to measure nitrogen?
a) Mixture of nitrogen and air
b) Water saturated mixture of nitrogen and oxygen
c) Mixture of nitrogen and hydrogen
d) Nitrogen

Answer: b [Reason:] Nitrogen meters are calibrated for water saturated mixture of nitrogen and oxygen. Hence, this calibration cannot be used for dry gases.

7. Why is nitrogen meters generally not calibrated for dry gases while measuring nitrogen?
a) It causes error
b) Range decreases
c) Reading tend to be non-linear
d) It cannot be measured

Answer: a [Reason:] Nitrogen meters are generally not calibrated for dry gases because it will lead to error in the reading. The error will be upto 2%.

8. In which of the following ways can nitrogen be calibrated for dry gases?
a) By modifying the amplifier
b) By adjusting the needle valve
c) By modifying the detector
d) By changing chopper frequency

Answer: b [Reason:] Nitrogen can be calibrated for dry gases by adjusting the needle valve. In this way, the error will be compensated.

9. The voltage required for striking the discharge in the presence of nitrogen is 1500V.
a) True
b) False