Question

part iv. use the following diagrams to answer the questions below.
a
b
c
d
e
f

1. which diagram or diagrams above represent a pure substance?
2. which diagram or diagrams represent a mixture?
3. which diagram or diagrams contain compounds only?

part v: use the diagrams below to answer the questions that follow.
a
b
c

1. which two of these pictures could be classified together?

why?

1. picture b and picture c both have black circle parts. why are they different?

part vi: sample standardized test questions on this topic. circle the correct answer.

1. a scientist combines oxygen and hydrogen to form water. this combination illustrates that water

a. is a mixture
b. is a compound
c. is an atom
d. is an element

1. sulfur (s), oxygen (o₂), water (h₂o), and sodium chloride (nacl) are all examples of pure substances. which of the following describes all pure substances?

a. a pure substance cannot ever be broken down into simpler substances
b. a pure substance is normally found as a solid at room temperature
c. a pure substance consists of only one type of element
d. a pure substance has a definite chemical composition

1. sugar is composed of bonded carbon, hydrogen, and oxygen. sugar is an example of...

a. an atom
b. a compound
c. an electron
d. a mixture

1. which of the following is formed when two elements combine chemically?

a. a compound
b. an electron
c. a mixture
d. an atom

Explanation:

Question 37

Step1: Recall definitions

A mixture is a combination of substances without chemical bonding. A compound is a substance formed by chemical bonding of two or more different elements. An atom is the basic unit of an element. An element is a pure substance with one type of atom.

Step2: Analyze the reaction

Oxygen (\(O_2\)) and hydrogen (\(H_2\)) combine chemically (via bonding) to form water (\(H_2O\)), which has two different elements (H and O) bonded. So water is a compound.

Step1: Evaluate each option

• Option a: Compounds (like \(H_2O\)) can be broken down into elements, so a is wrong.
• Option b: Substances like \(O_2\) (gas), \(H_2O\) (liquid), NaCl (solid) show pure substances can be in different states, so b is wrong.
• Option c: Compounds (e.g., \(H_2O\)) have multiple elements, so c is wrong.
• Option d: Pure substances (elements or compounds) have a definite chemical composition (e.g., \(H_2O\) always has 2 H and 1 O per molecule).

Step2: Confirm the correct option

Option d matches the definition of pure substances.

Step1: Recall definitions

An atom is a single particle. A compound is a substance with bonded different elements. An electron is a subatomic particle. A mixture has unbonded substances.

Step2: Analyze sugar's composition

Sugar has bonded C, H, O (different elements), so it's a compound.

Answer:

b. is a compound

Question 38