Question

1. a student finds two green powders that look the same. he wants to figure out if the two powders are the same or different substances. which of the following is the best method to use?

a. measure the mass, volume, and temperature of each powder and compare.
b. combine both green powders and see if there is a chemical reaction.
c. mix the two green powders together and then test the properties.
d. determine the density, solubility, and melting point of each powder and compare.

Explanation:

To determine if two substances are the same, we analyze the options:

• Option A: Mass, volume, and temperature are not unique identifiers of a substance (e.g., different amounts of the same substance can have different masses/volumes, and temperature is not an intrinsic property).
• Option B: Combining them to check for a reaction does not confirm if they are the same substance (reactions depend on chemical nature, not identity).
• Option C: Mixing them and testing properties would not isolate the properties of each original substance.
• Option D: Density, solubility, and melting point are intrinsic properties (independent of amount) that uniquely identify a substance. Comparing these properties for both powders will show if they are the same (matching properties) or different (distinct properties).

Answer:

D. Determine the density, solubility, and melting point of each powder and compare.