Optical Techniques

Question 1

1. What wavelength of light in the electromagnetic spectrum has the highest energy?
   a. 400 nm
   b. 500 nm
   c. 550 nm
   d. 660 nm

Answer 1

a. 400 nm

Question 2

2. The emission of light caused by a chemical reaction is:

a. chemiluminescence.
b. nephelometry.
c. turbidimetry.
d. fluorescence

Answer 2

a. chemiluminescence.

Question 3

3. The expression of the relationship between the concentration of a substance in solution and absorbance of light
   by that substance is referred to as Beer’s law. This relationship is expressed in a formula as:

a. log (1/T).
b. C = abc.
c. Io/Is × 100.
d. A = abc.

Answer 3

d. A = abc. ?

Question 4

4. Calculate the concentration of NADH, given that the
   absorbance at 340 nm is 0.5 and the molar absorptivity
   constant is 6220 M−1 cm−1. The cuvet has a path length of
   1 cm.
   a. 1.0 μM
   b. 10.0 μM
   c. 0.8 μM
   d. 8.0 μM
   e. 0.05 μM

Answer 4

c. 0.8 μM

Question 5

5. Which component of a single-beam spectrophotometer isolates radiant energy of a specific wavelength and
   excludes that of other wavelengths?
   a. Monochromator
   b. Entrance slit
   c. Cuvet
   d. Light source

Question 6

6. Measurement of the concentration of a substance that is
   performed by measuring scattered light at right angles to
   the incident light beam is called:

a. fluorometry.
b. atomic absorption.
c. turbidimetry.
d. nephelometry

Answer 6

d. nephelometry

Question 7

7. A solution that is identical to that of calibrating or
   unknown solutions and is used to set 100% T (zero
   absorbance) at the beginning of a photometric analysis is
   referred to as a:

a. standard solution.
b. calibrating solution.
c. reference blank.
d. reagent blank

Answer 7

d. reagent blank

Question 8

8. Calculate the transmittance of light when the absorbance
   in a sample is 0.5.
   a. 25.6%
   b. 40.1%
   c. 31.6%
   d. 10.9%

Answer 8

c. 31.6%

Question 9

9. In a flameless atomic absorption technique, the sample
   holder is typically a:

a. carbon rod in an enclosed chamber.
b. flame.
c. borosilicate glass cuvet.
d. reflective surface.

Answer 9

a. carbon rod in an enclosed chamber.

Question 10

10. The bandwidth of the spectral absorbance curve of an
    absorbing substance at a point equal to one-half of the
    maximum absorbance is referred to as the:

a. standard curve.
b. bandpass filter.
c. natural bandwidth.
d. monochromatic bandwidth.

Answer 10

c. natural bandwidth.