WGU D425 INTRO TO CHEMISTRY OBJECTIVE ASSESSMENT EXAM NEWEST 2026/ 2027 ACTUAL EXAM| COMPLETE REAL EXAM QUESTIONS AND CORRECT VERIFIED ANSWERS/ ALREADY GRADED A+ (MOST RECENT!!)

WGU D425 INTRO TO CHEMISTRY OBJECTIVE ASSESSMENT
EXAM NEWEST 2026/ 2027 ACTUAL EXAM| COMPLETE
REAL EXAM QUESTIONS AND CORRECT VERIFIED ANSWERS/ ALREADY
GRADED A+ (MOST RECENT!!)

SECTION 1: ATOMIC STRUCTURE & SUBAOMIC PARTICLES (Questions 1–30)
Q1. What is the smallest unit of an element that retains the chemical properties
of that element?
A) Molecule
B) Atom
C) Electron
D) Proton
Answer: B
Rationale: An atom is the fundamental building block of matter and the smallest
unit of an element that retains the chemical properties of that element.
Molecules are composed of two or more atoms bonded together. Electrons and
protons are subatomic particles that do not, by themselves, retain the properties
of an element. The atom is the basic unit of chemical identity. Understanding the
atom is foundational to all of chemistry because chemical reactions involve the
rearrangement of atoms, not their creation or destruction.

Q2. Which subatomic particle has a positive charge and is located in the nucleus
of an atom?
A) Electron
B) Neutron
C) Proton
D) Positron
Answer: C
Rationale: Protons are positively charged subatomic particles found in the nucleus
of an atom. The number of protons in the nucleus determines the atomic number
and therefore the identity of the element. Electrons are negatively charged and
orbit the nucleus. Neutrons have no charge (neutral) and are also found in the
nucleus. Positrons are antimatter particles with a positive charge but are not

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,found in ordinary atoms. The proton's positive charge is balanced by the
electron's negative charge in a neutral atom.

Q3. What is the charge and location of an electron?
A) Positive, in the nucleus
B) Negative, in the nucleus
C) Negative, orbiting the nucleus
D) Neutral, orbiting the nucleus
Answer: C
Rationale: Electrons are negatively charged subatomic particles that orbit the
nucleus in regions called electron shells or energy levels. They are much smaller
and lighter than protons and neutrons (approximately 1/1836 the mass of a
proton). The negative charge of electrons balances the positive charge of protons
in a neutral atom. Electrons are responsible for chemical bonding because they
are the outermost particles that interact with other atoms.

Q4. Which subatomic particle has no charge and contributes to the mass of an
atom?
A) Proton
B) Electron
C) Neutron
D) Ion
Answer: C
Rationale: Neutrons are neutral (uncharged) subatomic particles located in the
nucleus. They contribute significantly to the atomic mass along with protons. The
number of neutrons can vary among atoms of the same element, creating
isotopes. While electrons have negligible mass, neutrons have a mass nearly
identical to that of protons (approximately 1 atomic mass unit). Ions are charged
atoms, not subatomic particles.

Q5. What is the mass number of an atom?
A) The number of protons only
B) The number of neutrons only

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,C) The total number of protons and neutrons
D) The total number of protons and electrons
Answer: C
Rationale: The mass number (A) is the total count of nucleons—protons and
neutrons—in the nucleus of an atom. Electrons have such a small mass
(approximately 1/1836 of a proton) that they are excluded from the mass number
calculation. The mass number is a whole number and differs from the atomic
mass, which is a weighted average of all isotopes. For example, a carbon-12 atom
has 6 protons and 6 neutrons, giving a mass number of 12.

Q6. What is the atomic number of an atom?
A) The number of neutrons
B) The number of protons
C) The number of electrons plus protons
D) The number of neutrons plus protons
Answer: B
Rationale: The atomic number (Z) is defined as the number of protons in the
nucleus of an atom. This number uniquely identifies an element; no two elements
have the same atomic number. In a neutral atom, the atomic number also equals
the number of electrons. The atomic number is the fundamental organizing
principle of the periodic table, as elements are arranged in order of increasing
atomic number.

Q7. Isotopes of the same element have different numbers of:
A) Protons
B) Electrons
C) Neutrons
D) Positrons
Answer: C
Rationale: Isotopes are atoms of the same element (same number of protons)
that have different numbers of neutrons. Because they have different neutron
counts, they have different mass numbers. Isotopes of an element have identical
chemical properties because chemical behavior is determined by the electron

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, configuration, which remains the same. For example, carbon-12, carbon-13, and
carbon-14 all have 6 protons but have 6, 7, and 8 neutrons, respectively.

Q8. Which of the following is NOT a subatomic particle?
A) Proton
B) Neutron
C) Electron
D) Molecule
Answer: D
Rationale: Protons, neutrons, and electrons are the three primary subatomic
particles that make up atoms. A molecule is a chemical entity composed of two or
more atoms held together by covalent bonds. Molecules are larger units of
matter, not subatomic particles. The distinction between atoms (single particles)
and molecules (groups of bonded atoms) is fundamental to understanding
chemical structure.

Q9. What is the charge of a neutron?
A) +1
B) -1
C) 0
D) +2
Answer: C
Rationale: Neutrons are electrically neutral, meaning they carry no charge (zero).
They are found in the nucleus alongside protons. The neutrality of neutrons
allows them to contribute to the nucleus's mass without causing electrostatic
repulsion between the positively charged protons. Without neutrons, the protons
in the nucleus would repel each other and the nucleus would be unstable.

Q10. Which subatomic particle has the smallest mass?
A) Proton
B) Neutron
C) Electron
D) Nucleus

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