TExES Chemistry 7–12 Certification
Examination Questions and Correct
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Rationales 2026 Q&A | Instant
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1. Which particle determines the identity of an element?
A. Neutron
B. Electron
C. Ion
D. Proton
Correct Answer: D. Proton
Rationale: The number of protons in an atom's nucleus is its atomic number and
defines the element.
2. The atomic number of an element represents the number of:
A. Neutrons
B. Electrons plus neutrons
C. Mass units
D. Protons
Correct Answer: D. Protons
Rationale: Atomic number equals the number of protons in the nucleus.
,3. The mass number of an atom equals the total number of:
A. Electrons and protons
B. Electrons and neutrons
C. Protons only
D. Protons and neutrons
Correct Answer: D. Protons and neutrons
Rationale: Nearly all atomic mass comes from protons and neutrons in the
nucleus.
4. Isotopes of an element differ in their number of:
A. Protons
B. Electrons
C. Atomic numbers
D. Neutrons
Correct Answer: D. Neutrons
Rationale: Isotopes have the same number of protons but different numbers of
neutrons.
5. Which subatomic particle has a negative charge?
A. Proton
B. Neutron
C. Nucleus
D. Electron
Correct Answer: D. Electron
Rationale: Electrons carry a −1 electrical charge.
6. Which scientist proposed the nuclear model of the atom?
,A. Dalton
B. Thomson
C. Bohr
D. Ernest Rutherford
Correct Answer: D. Ernest Rutherford
Rationale: Rutherford's gold foil experiment demonstrated that atoms contain a
small, dense nucleus.
7. Which atomic model describes electrons existing in specific energy levels?
A. Dalton model
B. Thomson model
C. Nuclear model
D. Bohr model
Correct Answer: D. Bohr model
Rationale: Bohr proposed that electrons occupy specific quantized energy levels.
8. The maximum number of electrons in the first energy level is:
A. 1
B. 4
C. 8
D. 2
Correct Answer: D. 2
Rationale: The first energy level contains only the 1s orbital, which holds two
electrons.
9. Which principle states that electrons fill lower-energy orbitals before higher-
energy orbitals?
, A. Hund’s rule
B. Pauli exclusion principle
C. Octet rule
D. Aufbau principle
Correct Answer: D. Aufbau principle
Rationale: The Aufbau principle describes the order of orbital filling.
10. The electrons in the outermost energy level are called:
A. Core electrons
B. Nuclear electrons
C. Inner electrons
D. Valence electrons
Correct Answer: D. Valence electrons
Rationale: Valence electrons determine an element's chemical behavior and
bonding patterns.
11. Which element is classified as an alkali metal?
A. Calcium
B. Chlorine
C. Neon
D. Sodium
Correct Answer: D. Sodium
Rationale: Sodium is a Group 1 element and an alkali metal.
12. Elements in the same group on the periodic table have similar:
A. Atomic masses
B. Number of neutrons
Examination Questions and Correct
Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant
Download Pdf
1. Which particle determines the identity of an element?
A. Neutron
B. Electron
C. Ion
D. Proton
Correct Answer: D. Proton
Rationale: The number of protons in an atom's nucleus is its atomic number and
defines the element.
2. The atomic number of an element represents the number of:
A. Neutrons
B. Electrons plus neutrons
C. Mass units
D. Protons
Correct Answer: D. Protons
Rationale: Atomic number equals the number of protons in the nucleus.
,3. The mass number of an atom equals the total number of:
A. Electrons and protons
B. Electrons and neutrons
C. Protons only
D. Protons and neutrons
Correct Answer: D. Protons and neutrons
Rationale: Nearly all atomic mass comes from protons and neutrons in the
nucleus.
4. Isotopes of an element differ in their number of:
A. Protons
B. Electrons
C. Atomic numbers
D. Neutrons
Correct Answer: D. Neutrons
Rationale: Isotopes have the same number of protons but different numbers of
neutrons.
5. Which subatomic particle has a negative charge?
A. Proton
B. Neutron
C. Nucleus
D. Electron
Correct Answer: D. Electron
Rationale: Electrons carry a −1 electrical charge.
6. Which scientist proposed the nuclear model of the atom?
,A. Dalton
B. Thomson
C. Bohr
D. Ernest Rutherford
Correct Answer: D. Ernest Rutherford
Rationale: Rutherford's gold foil experiment demonstrated that atoms contain a
small, dense nucleus.
7. Which atomic model describes electrons existing in specific energy levels?
A. Dalton model
B. Thomson model
C. Nuclear model
D. Bohr model
Correct Answer: D. Bohr model
Rationale: Bohr proposed that electrons occupy specific quantized energy levels.
8. The maximum number of electrons in the first energy level is:
A. 1
B. 4
C. 8
D. 2
Correct Answer: D. 2
Rationale: The first energy level contains only the 1s orbital, which holds two
electrons.
9. Which principle states that electrons fill lower-energy orbitals before higher-
energy orbitals?
, A. Hund’s rule
B. Pauli exclusion principle
C. Octet rule
D. Aufbau principle
Correct Answer: D. Aufbau principle
Rationale: The Aufbau principle describes the order of orbital filling.
10. The electrons in the outermost energy level are called:
A. Core electrons
B. Nuclear electrons
C. Inner electrons
D. Valence electrons
Correct Answer: D. Valence electrons
Rationale: Valence electrons determine an element's chemical behavior and
bonding patterns.
11. Which element is classified as an alkali metal?
A. Calcium
B. Chlorine
C. Neon
D. Sodium
Correct Answer: D. Sodium
Rationale: Sodium is a Group 1 element and an alkali metal.
12. Elements in the same group on the periodic table have similar:
A. Atomic masses
B. Number of neutrons
