Question

first. then determine whether that is a pure substance or mixture. a pure substance can elements, mixture of compounds, or a
1
pure substances
14
2
mixture
mixture of compounds
15
3
pure substance
element
16
4
17
5
18
6
19

Explanation:

Step1: Identify particle type

All particles are identical 2-atom groups.

Step2: Classify as pure substance

Only one type of particle exists, so it is a pure substance.

Step3: Classify as compound

Each particle has 2 identical atoms? No, wait—wait, identical atoms bonded form an element. Wait, correction: identical atoms make an element. All particles are same, pure substance, element.
Wait, re-clarify: The diagram shows multiple identical molecules, each made of 2 identical red atoms. So:

Step1: Identify particle uniformity

All particles are identical.
<Expression>Uniform particle set: same 2-atom units</Expression>

Step2: Classify pure substance

Single particle type = pure substance.
<Expression>Pure Substance (only one particle type)</Expression>

Step3: Classify as element

Particles have identical atoms.
<Expression>Element (particles of identical atoms)</Expression>

Answer:

For row 4 (matching diagram 3):

• # OF DIFFERENT SUBSTANCES: 1
• PURE SUBSTANCE OR MIXTURE: Pure Substance
• ELEMENT, COMPOUND OR MIXTURE: Element