WGU D425 Introduction to Chemistry | PA & OA |
Explore New 107 Questions and Answers | 100%
Correct | Latest 2026 Update with Complete
Solutions and Exam Preparation Material
Q1. What is the charge of a neutron?
a) Positive
b) Negative
c) Neutral
d) Variable
Correct Answer: c) Neutral
Rationale: Neutrons are subatomic particles located in the
nucleus with no net electric charge, stabilizing the nucleus
alongside protons.
Q2. An atom has 12 protons and 14 neutrons. What is its
mass number?
a) 12
b) 14
1
,c) 26
d) 24
Correct Answer: c) 26
Rationale: Mass number = protons + neutrons = 12 + 14
= 26.
Q3. Isotopes of the same element differ in the number of:
a) Protons
b) Electrons
c) Neutrons
d) Orbital shells
Correct Answer: c) Neutrons
Rationale: Isotopes have the same atomic number (protons)
but different mass numbers due to varying neutron counts.
Q4. Which subatomic particle determines the identity of
an element?
a) Proton
b) Neutron
c) Electron
2
,d) Positron
Correct Answer: a) Proton
Rationale: The atomic number (number of protons)
uniquely defines an element.
Q5. Calculate the average atomic mass of chlorine if it is
75.77% Cl-35 (34.97 amu) and 24.23% Cl-37 (36.97
amu).
a) 35.45 amu
b) 35.97 amu
c) 35.00 amu
d) 36.50 amu
Correct Answer: a) 35.45 amu
Rationale: (0.7577 × 34.97) + (0.2423 × 36.97) =
26.49 + 8.96 = 35.45 amu.
Q6. Which element has the electron configuration 1s² 2s²
2p⁶ 3s² 3p⁵ ?
a) Argon
b) Chlorine
3
, c) Sulfur
d) Phosphorus
Correct Answer: b) Chlorine
Rationale: 1s² 2s² 2p⁶ 3s² 3p⁵ totals 17 electrons,
which is atomic number 17, chlorine.
Q7. How many valence electrons does carbon (atomic
number 6) have?
a) 2
b) 4
c) 6
d) 8
Correct Answer: b) 4
Rationale: Carbon’s electron configuration ends with 2s²
2p² → 4 valence electrons.
Q8. Which of the following has the largest atomic radius?
a) Li
b) Be
c) B
4
Explore New 107 Questions and Answers | 100%
Correct | Latest 2026 Update with Complete
Solutions and Exam Preparation Material
Q1. What is the charge of a neutron?
a) Positive
b) Negative
c) Neutral
d) Variable
Correct Answer: c) Neutral
Rationale: Neutrons are subatomic particles located in the
nucleus with no net electric charge, stabilizing the nucleus
alongside protons.
Q2. An atom has 12 protons and 14 neutrons. What is its
mass number?
a) 12
b) 14
1
,c) 26
d) 24
Correct Answer: c) 26
Rationale: Mass number = protons + neutrons = 12 + 14
= 26.
Q3. Isotopes of the same element differ in the number of:
a) Protons
b) Electrons
c) Neutrons
d) Orbital shells
Correct Answer: c) Neutrons
Rationale: Isotopes have the same atomic number (protons)
but different mass numbers due to varying neutron counts.
Q4. Which subatomic particle determines the identity of
an element?
a) Proton
b) Neutron
c) Electron
2
,d) Positron
Correct Answer: a) Proton
Rationale: The atomic number (number of protons)
uniquely defines an element.
Q5. Calculate the average atomic mass of chlorine if it is
75.77% Cl-35 (34.97 amu) and 24.23% Cl-37 (36.97
amu).
a) 35.45 amu
b) 35.97 amu
c) 35.00 amu
d) 36.50 amu
Correct Answer: a) 35.45 amu
Rationale: (0.7577 × 34.97) + (0.2423 × 36.97) =
26.49 + 8.96 = 35.45 amu.
Q6. Which element has the electron configuration 1s² 2s²
2p⁶ 3s² 3p⁵ ?
a) Argon
b) Chlorine
3
, c) Sulfur
d) Phosphorus
Correct Answer: b) Chlorine
Rationale: 1s² 2s² 2p⁶ 3s² 3p⁵ totals 17 electrons,
which is atomic number 17, chlorine.
Q7. How many valence electrons does carbon (atomic
number 6) have?
a) 2
b) 4
c) 6
d) 8
Correct Answer: b) 4
Rationale: Carbon’s electron configuration ends with 2s²
2p² → 4 valence electrons.
Q8. Which of the following has the largest atomic radius?
a) Li
b) Be
c) B
4
