Final answer:
Based on the information provided, sulfur being yellow and gold's ability to be stretched into wires are physical properties, while flammability is a chemical property. Hence, the observations that represent physical properties are 'c) Gold can be stretched into very thin wires' and 'c) The alcohol in many thermometers freezes at about -40 degrees Fahrenheit'. The correct answer is b) 3 and 4.
Step-by-step explanation:
The student's question is asking to identify which observations represent physical properties of a substance. Physical properties are characteristics of a substance that can be observed or measured without changing the substance's composition. Examples include color, density, and melting and boiling points. In contrast, chemical properties describe a substance's ability to undergo changes that transform it into different substances, such as reactivity or flammability.
Based on the given exercises and information:
- Sulfur being yellow represents a physical property.
- Gold being able to be stretched into thin wires represents a physical property.
- The freezing point of alcohol at about -40 degrees Fahrenheit represents a physical property.
- Density is a physical property.
- Flammability is a chemical property.
Therefore, the correct options that represent physical properties would be c) Gold can be stretched into thin wires (3 from question 3) and c) The alcohol in many thermometers freezes at about -40 degrees Fahrenheit (4 from question 4). Option c) 2 and 3 cannot be correct because 2 from question 2 (Steel wool burns when ignited by a flame) represents a chemical property. So, by process of elimination and identifying the nature of the properties, the correct answer would be option 'b) 3 and 4', which are both physical properties.