Final answer:
When changing the penny in different ways, various differences may be observed in its appearance or properties. Heat can cause a brown spot to form on the penny when iodine is added. Observations should be recorded in a data chart with quantitative measurements, control experiment details, statistical trends, and qualitative descriptions. The correct answer is option D .
Step-by-step explanation:
When changing the penny in different ways, you may observe various differences in its appearance or properties. For example, if you scratch the surface of the penny, you may observe that the copper layer underneath is exposed. If you heat the penny with iodine, you may observe a brown spot forming on the penny due to a reaction between the iodine and the metal.
To record your observations, you can create a data chart with columns for different variables. In column A, you can record the quantitative measurements, such as the weight or size of the penny. In column B, you can describe the control experiment that you conducted to compare against the other variations. In column C, you can analyze any statistical trends you observed in your data. In column D, you can submit qualitative descriptions of your observations, such as the color change or physical changes you observed.
In chemistry experiments, observations are crucial for formulating hypotheses and testing them. Qualitative observations describe events without numbers, while quantitative observations involve measurements. A systematic approach to experiments, with careful consideration of variables, leads to valid and reproducible conclusions.