Introductory Chemistry Exam
Course: Introductory Chemistry
Level: High School / College
Document Type: Exam Questions with Model Answers
Time: 2 Hours
Instructions: Answer ALL questions.
, QUESTION 1 (10 MARKS)
Question: Define an element.
Answer: An element is a pure substance composed of only one type of atom and cannot be
broken down into simpler substances by chemical means.
QUESTION 2 (10 MARKS)
Question: What is an atom?
Answer: An atom is the smallest unit of an element that retains the chemical identity and
properties of that element.
QUESTION 3 (15 MARKS)
Question: Describe the structure of an atom, naming its main subatomic particles.
Answer: An atom consists of a central nucleus containing protons and neutrons.
Surrounding the nucleus are electrons that occupy specific energy levels. Protons carry a
positive charge, neutrons have no charge, and electrons carry a negative charge.
QUESTION 4 (10 MARKS)
Question: Define atomic number and state its significance.
Answer: The atomic number is the number of protons present in the nucleus of an atom. It
identifies the element and is equal to the number of electrons in a neutral atom.
QUESTION 5 (10 MARKS)
Question: What is atomic mass?
Answer: Atomic mass is the total mass of an atom, which is determined by the combined
number of protons and neutrons in its nucleus.
Course: Introductory Chemistry
Level: High School / College
Document Type: Exam Questions with Model Answers
Time: 2 Hours
Instructions: Answer ALL questions.
, QUESTION 1 (10 MARKS)
Question: Define an element.
Answer: An element is a pure substance composed of only one type of atom and cannot be
broken down into simpler substances by chemical means.
QUESTION 2 (10 MARKS)
Question: What is an atom?
Answer: An atom is the smallest unit of an element that retains the chemical identity and
properties of that element.
QUESTION 3 (15 MARKS)
Question: Describe the structure of an atom, naming its main subatomic particles.
Answer: An atom consists of a central nucleus containing protons and neutrons.
Surrounding the nucleus are electrons that occupy specific energy levels. Protons carry a
positive charge, neutrons have no charge, and electrons carry a negative charge.
QUESTION 4 (10 MARKS)
Question: Define atomic number and state its significance.
Answer: The atomic number is the number of protons present in the nucleus of an atom. It
identifies the element and is equal to the number of electrons in a neutral atom.
QUESTION 5 (10 MARKS)
Question: What is atomic mass?
Answer: Atomic mass is the total mass of an atom, which is determined by the combined
number of protons and neutrons in its nucleus.
