Question 1

Which statement best describes the principle behind spectroscopy?

Accepted Answer

It is the study of the absorption and emission of light and other radiation by matter.

Question 2

During a flame test, what causes the observed flame color for a metallic element?

Accepted Answer

The excitation and subsequent emission of light by electrons in the metal atoms.

Question 3

Which of the following is a major limitation of the flame test technique?

Accepted Answer

It is qualitative only and cannot determine the concentration of metals.

Question 4

A student performs a flame test and observes a green flame. Which metal is most likely present?

Accepted Answer

Copper

Question 5

Which of the following best explains why atomic absorption spectroscopy (AAS) is more suitable than flame tests for analyzing mixtures of metals?

Accepted Answer

AAS is highly selective and can quantitatively determine the concentration of individual metals even in mixtures.

Question 6

In atomic absorption spectroscopy, what is the role of the calibration curve?

Accepted Answer

It is used to determine the concentration of an unknown sample by comparing its absorbance to those of known standards.

Question 7

Which equation best represents the relationship between absorbance ($A$) and concentration ($c$) in atomic absorption spectroscopy?

Accepted Answer

$A = \epsilon l c$

Question 8

A calibration curve for copper in water yields the equation $A = 0.25c + 0.02$, where $A$ is absorbance and $c$ is concentration in mg/L. If an unknown sample has an absorbance of $0.27$, what is its copper concentration?

Accepted Answer

$c = 1.0$ mg/L

Question 9

Which of the following is NOT an advantage of atomic absorption spectroscopy (AAS) over flame tests?

Accepted Answer

AAS can only provide qualitative results.

Question 10

Why is it important to use a non-luminous Bunsen burner in flame tests?

Accepted Answer

To avoid interference from the yellow color of the flame, which can mask the emission colors of the metals.

Question 11

Which step in atomic absorption spectroscopy ensures that only the desired wavelength of light reaches the detector?

Accepted Answer

A wavelength filter selects the desired wavelength of light.

Question 12

A scientist wants to determine the concentration of lead in a water sample. Which technique should they use for the most accurate and sensitive measurement?

Accepted Answer

Atomic absorption spectroscopy (AAS)

Question 13

Which of the following metals would produce a red flame in a flame test?

Accepted Answer

Strontium

Question 14

If a mixture of sodium and potassium is analyzed by flame test, what is a likely outcome?

Accepted Answer

The flame color may be confusing or inaccurate due to overlapping emissions.

Question 15

Which property of AAS allows it to detect elements in concentrations as low as micrograms per liter?

Accepted Answer

Its high sensitivity and selectivity for specific wavelengths absorbed by target atoms.

Question 16

A calibration curve is constructed by plotting which two variables?

Accepted Answer

Absorbance (y-axis) vs. concentration (x-axis)

Question 17

Which of the following statements about emission spectra is correct?

Accepted Answer

Each element produces a unique emission spectrum that can be used for identification.

Question 18

A solution containing an unknown metal is analyzed by AAS and gives an absorbance of $0.50$. The calibration curve equation is $A = 0.40c + 0.10$. What is the concentration of the metal in the solution?

Accepted Answer

$c = 1.0$

Question 19

Which of the following is a real-world application of atomic absorption spectroscopy?

Accepted Answer

Measuring trace amounts of heavy metals in drinking water.

Spectroscopy: Flame Test and Atomic Absorption Spectroscopy (AAS) Study Notes

Study Guide - Practice Questions

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