Question

a student wants to conduct an investigation that will determine a physical property of an unknown substance. which of these procedures would best measure a physical property of the unknown sample?
a

1. using tongs, hold the sample over a flame
2. observe if the sample catches on fire
3. record your observations

b

1. break the sample into a fine powder
2. add the powder to a 500 ml beaker
3. add 300 ml of water to the beaker and use to stirring rod to mix
4. using a dropper, add 4 drops of universal ph indicator to the solution
5. observe any color change in the sample
6. record your observations

c

1. create an acidic solution by adding 5 ml vinegar to 100 ml water
2. place the sample into the acidic solution
3. observe if the sample begins to fizz in the solution
4. record your observations

d

1. place the sample in a resealable, zip-top bag
2. firmly close the zip-top bag
3. lightly tap the sample with a hammer
4. observe if the sample dents, breaks, or shatters

Explanation:

To determine a physical property, we analyze each option:

• Option A: Observing if a sample catches fire tests flammability, a chemical property (involves combustion, a chemical change).
• Option B: Adding a pH indicator and observing color change relates to chemical reactions (determining acidity/alkalinity, a chemical property).
• Option C: Observing fizzing in an acidic solution indicates a chemical reaction (like metal reacting with acid to produce gas), a chemical property.
• Option D: Tapping the sample to see if it dents, breaks, or shatters tests hardness/ductility, which are physical properties (no chemical change occurs, just a change in physical form).

Answer:

D. 1. Place the sample in a resealable, zip - top bag; 2. Firmly close the zip - top bag; 3. Lightly tap the sample with a hammer; 4. Observe if the sample dents, breaks, or shatters