WGU D425 Intro to Chemistry Objective
Assessment Actual Exam 2025/2026 |
Questions with Verified Answers | 100%
Correct | Pass Guaranteed
SECTION 1: MATTER, MEASUREMENTS, AND ATOMIC
THEORY (Questions 1-30)
Q1: How is matter classified?
Correct ,,,answer,,,: Pure substances and mixtures
Rationale: Matter is anything that has mass and occupies volume. It is
classified into two main categories: pure substances (elements and
compounds with fixed composition) and mixtures (physical
combinations of two or more substances that retain their individual
identities). Air is an example of a mixture, while water is a pure
substance .
Q2: What is an element?
,Correct ,,,answer,,,: A pure substance consisting of one type of atom
that cannot be broken down chemically
Rationale: Elements are fundamental substances that cannot be
decomposed into simpler substances by chemical means. There are 118
known elements, each represented by a unique symbol on the periodic
table. Examples include carbon (C), oxygen (O), and gold (Au) .
Q3: What is a compound?
Correct ,,,answer,,,: A pure substance made up of two or more different
elements chemically bonded together in a fixed ratio
Rationale: Compounds are pure substances formed when atoms of
different elements chemically combine in specific ratios. Water (H₂O)
contains two hydrogen atoms for every oxygen atom. Table salt (NaCl)
has a 1:1 ratio of sodium to chlorine. Compounds can only be broken
down by chemical means, not physical methods .
Q4: What is a mixture?
Correct ,,,answer,,,: A physical blend of two or more pure substances
where each substance retains its own identity and properties
Rationale: Mixtures are physical combinations, not chemical bonds.
The components can be separated by physical means such as filtration or
evaporation. Unlike compounds, mixtures have variable composition.
Saltwater, air, and salad dressing are examples .
,Q5: What are the three phases (states) of matter?
Correct ,,,answer,,,: Solid, liquid, and gas
Rationale: Matter exists in three primary states. Solids have definite
shape and volume with particles in fixed positions. Liquids have definite
volume but no definite shape. Gases have no definite shape or volume .
Q6: What is a homogeneous mixture?
Correct ,,,answer,,,: A mixture with uniform composition throughout;
components are evenly distributed and not easily distinguished
Rationale: Homogeneous mixtures, also called solutions, have the same
composition throughout any sample. Saltwater (uniform salt
distribution), air, and brass (copper-zinc alloy) are examples. The prefix
"homo-" means "same" .
Q7: What is a heterogeneous mixture?
Correct ,,,answer,,,: A mixture that is NOT uniform in composition;
components are not evenly distributed
Rationale: Heterogeneous mixtures have visibly different components
or regions. The prefix "hetero-" means "different." Salad dressing, Chex
, mix, rocks, and chicken noodle soup are examples where distinct
substances can be seen .
Q8: What is the law of conservation of mass?
Correct ,,,answer,,,: Matter cannot be created or destroyed in chemical
reactions
Rationale: This fundamental law, established by Lavoisier, states that
total mass remains constant during any chemical reaction. The mass of
reactants equals the mass of products. This principle is the basis for
balancing chemical equations. Matter only changes form—it is neither
created nor destroyed .
Q9: What is an atom?
Correct ,,,answer,,,: The smallest unit of matter that retains the
properties of an element
Rationale: Atoms are the basic building blocks of matter. Each atom
consists of a nucleus (containing protons and neutrons) surrounded by an
electron cloud. The atomic number (number of protons) defines which
element the atom represents .
Q10: What is the atomic number?
Assessment Actual Exam 2025/2026 |
Questions with Verified Answers | 100%
Correct | Pass Guaranteed
SECTION 1: MATTER, MEASUREMENTS, AND ATOMIC
THEORY (Questions 1-30)
Q1: How is matter classified?
Correct ,,,answer,,,: Pure substances and mixtures
Rationale: Matter is anything that has mass and occupies volume. It is
classified into two main categories: pure substances (elements and
compounds with fixed composition) and mixtures (physical
combinations of two or more substances that retain their individual
identities). Air is an example of a mixture, while water is a pure
substance .
Q2: What is an element?
,Correct ,,,answer,,,: A pure substance consisting of one type of atom
that cannot be broken down chemically
Rationale: Elements are fundamental substances that cannot be
decomposed into simpler substances by chemical means. There are 118
known elements, each represented by a unique symbol on the periodic
table. Examples include carbon (C), oxygen (O), and gold (Au) .
Q3: What is a compound?
Correct ,,,answer,,,: A pure substance made up of two or more different
elements chemically bonded together in a fixed ratio
Rationale: Compounds are pure substances formed when atoms of
different elements chemically combine in specific ratios. Water (H₂O)
contains two hydrogen atoms for every oxygen atom. Table salt (NaCl)
has a 1:1 ratio of sodium to chlorine. Compounds can only be broken
down by chemical means, not physical methods .
Q4: What is a mixture?
Correct ,,,answer,,,: A physical blend of two or more pure substances
where each substance retains its own identity and properties
Rationale: Mixtures are physical combinations, not chemical bonds.
The components can be separated by physical means such as filtration or
evaporation. Unlike compounds, mixtures have variable composition.
Saltwater, air, and salad dressing are examples .
,Q5: What are the three phases (states) of matter?
Correct ,,,answer,,,: Solid, liquid, and gas
Rationale: Matter exists in three primary states. Solids have definite
shape and volume with particles in fixed positions. Liquids have definite
volume but no definite shape. Gases have no definite shape or volume .
Q6: What is a homogeneous mixture?
Correct ,,,answer,,,: A mixture with uniform composition throughout;
components are evenly distributed and not easily distinguished
Rationale: Homogeneous mixtures, also called solutions, have the same
composition throughout any sample. Saltwater (uniform salt
distribution), air, and brass (copper-zinc alloy) are examples. The prefix
"homo-" means "same" .
Q7: What is a heterogeneous mixture?
Correct ,,,answer,,,: A mixture that is NOT uniform in composition;
components are not evenly distributed
Rationale: Heterogeneous mixtures have visibly different components
or regions. The prefix "hetero-" means "different." Salad dressing, Chex
, mix, rocks, and chicken noodle soup are examples where distinct
substances can be seen .
Q8: What is the law of conservation of mass?
Correct ,,,answer,,,: Matter cannot be created or destroyed in chemical
reactions
Rationale: This fundamental law, established by Lavoisier, states that
total mass remains constant during any chemical reaction. The mass of
reactants equals the mass of products. This principle is the basis for
balancing chemical equations. Matter only changes form—it is neither
created nor destroyed .
Q9: What is an atom?
Correct ,,,answer,,,: The smallest unit of matter that retains the
properties of an element
Rationale: Atoms are the basic building blocks of matter. Each atom
consists of a nucleus (containing protons and neutrons) surrounded by an
electron cloud. The atomic number (number of protons) defines which
element the atom represents .
Q10: What is the atomic number?
