Know Your Lab Instruments

Science and Technology · 10 questions

Questions about laboratory instruments, their measurement principles, readings, and operating conditions.

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1. In a UV-visible spectrophotometer, under suitable conditions, what quantity is absorbance most directly related to?

   1. Solution density
   2. Solution temperature
   3. Solution concentration
   4. Solution pressure
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   C) Solution concentration

2. In a compound microscope, which objective property improves resolving power when other conditions are equal?

   1. Numerical aperture
   2. Field-of-view diameter
   3. Tube length
   4. Eyepiece magnification
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   A) Numerical aperture

3. In a glass-electrode pH measurement, what signal does the meter primarily detect between the electrodes?

   1. Electric current
   2. Potential difference
   3. Mass difference
   4. Light intensity
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   B) Potential difference

4. When an analytical balance is tared with a container, what quantity does it display for the added sample?

   1. Pressure
   2. Volume
   3. Density
   4. Mass
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   D) Mass

5. The volume delivered from a burette is found from the difference between which two readings?

   1. Final and initial burette readings
   2. Final and initial masses
   3. Final and initial temperatures
   4. Final and initial pH values
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   A) Final and initial burette readings

6. Which optical property underlies a refractometer’s measurement of a liquid’s refractive index?

   1. Light absorption
   2. Light polarization
   3. Light scattering
   4. Light refraction
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   D) Light refraction

7. In a constant-volume bomb calorimeter, the measured heat of combustion equals which thermodynamic change?

   1. Change in enthalpy
   2. Change in entropy
   3. Change in Gibbs energy
   4. Change in internal energy
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   D) Change in internal energy

8. At the same rotational speed, what quantity increases if a centrifuge rotor’s radius is increased?

   1. Sample mass
   2. Relative centrifugal force
   3. Sample refractive index
   4. Sample pH
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   B) Relative centrifugal force

9. What is the primary role of the carrier gas in gas chromatography?

   1. Weighing the sample
   2. Calibrating the detector signal
   3. Moving the sample through the column
   4. Cooling the column
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   C) Moving the sample through the column

10. What measurable signal does a thermocouple produce when there is a temperature difference between its junctions?

    1. Thermoelectric voltage
    2. Optical density
    3. Magnetic flux
    4. Sound pressure
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    A) Thermoelectric voltage