, Portage Learning CHEM 103 General
Chemistry I Module 2 Exam
Question 11
How many neutrons are present in an atom of the isotope \(^{131}_{\ \ 53}\text{I}\)?
A) 53
B) 78
C) 131
D) 184
Answer: B) 78
Rationale: The number of neutrons is determined by subtracting the atomic number (\(Z
= 53\), subscripts) from the mass number (\(A = 131\), superscripts). Calculating \(131 -
53 = 78\) neutrons.
Question 12
Calculate the wavelength (in meters) of an electromagnetic wave that possesses a
frequency of \(4.50 \times 10^{14}\text{ s}^{-1}\). \([\text{Speed of light, } c = 3.00 \times
10^8\text{ m/s}]\).
A) \(1.35 \times 10^{23}\text{ m}\)
B) \(6.67 \times 10^{-7}\text{ m}\)
C) \(1.50 \times 10^{-6}\text{ m}\)
D) \(6.67 \times 10^6\text{ m}\)
Answer: B) \(6.67 \times 10^{-7}\text{ m}\)
Rationale: Use the wave equation: \(c = \lambda\nu\). Rearranging to isolate wavelength
gives \(\lambda = c / \nu\). Substituting the values: \(\lambda = (3.00 \times 10^8\text{
m/s}) / (4.50 \times 10^{14}\text{ s}^{-1}) = 6.6667 \times 10^{-7}\text{ m}\), which rounds
to \(6.67 \times 10^{-7}\text{ m}\) using three significant figures.
Question 13
Which of the following electronic configurations represents an excited state of a neutral
nitrogen atom rather than its ground state?
A) \(1s^{2}2s^{2}2p^{3}\)
B) \(1s^{2}2s^{2}2p^{2}3s^{1}\)
C) \(1s^{2}2s^{1}2p^{4}\)
D) \(1s^{2}2s^{2}2p^{4}\)
Chemistry I Module 2 Exam
Question 11
How many neutrons are present in an atom of the isotope \(^{131}_{\ \ 53}\text{I}\)?
A) 53
B) 78
C) 131
D) 184
Answer: B) 78
Rationale: The number of neutrons is determined by subtracting the atomic number (\(Z
= 53\), subscripts) from the mass number (\(A = 131\), superscripts). Calculating \(131 -
53 = 78\) neutrons.
Question 12
Calculate the wavelength (in meters) of an electromagnetic wave that possesses a
frequency of \(4.50 \times 10^{14}\text{ s}^{-1}\). \([\text{Speed of light, } c = 3.00 \times
10^8\text{ m/s}]\).
A) \(1.35 \times 10^{23}\text{ m}\)
B) \(6.67 \times 10^{-7}\text{ m}\)
C) \(1.50 \times 10^{-6}\text{ m}\)
D) \(6.67 \times 10^6\text{ m}\)
Answer: B) \(6.67 \times 10^{-7}\text{ m}\)
Rationale: Use the wave equation: \(c = \lambda\nu\). Rearranging to isolate wavelength
gives \(\lambda = c / \nu\). Substituting the values: \(\lambda = (3.00 \times 10^8\text{
m/s}) / (4.50 \times 10^{14}\text{ s}^{-1}) = 6.6667 \times 10^{-7}\text{ m}\), which rounds
to \(6.67 \times 10^{-7}\text{ m}\) using three significant figures.
Question 13
Which of the following electronic configurations represents an excited state of a neutral
nitrogen atom rather than its ground state?
A) \(1s^{2}2s^{2}2p^{3}\)
B) \(1s^{2}2s^{2}2p^{2}3s^{1}\)
C) \(1s^{2}2s^{1}2p^{4}\)
D) \(1s^{2}2s^{2}2p^{4}\)
