15. how many meters is 8.72 centimeters?
a. 872
b. 0.0872
c. 8.72
d. 8720
16. the ability to be pounded into thin sheets is known as
a. solubility
b. malleability
c. ductility
d. electromagnetism
17. which of the following is an example of a physical change?
a. burning wood
b. dying hair
c. leaves changing color in autumn
d. cutting a piece of paper during art class
18. which of the following would be an example of a chemical change?
a. burning wood
b. dying hair
c. leaves changing color
d. all of the above
19. a salad is classified as a(n) ________.
a. homogeneous mixture
b. heterogeneous mixture
c. compound
d. element
20. nacl is classified as a(n) ________.
a. homogeneous mixture
b. heterogeneous mixture
c. compound
d. element
21. nitrogen is classified as a(n) ________.

Question

Accepted Answer

### Question 15
# Explanation:
## Step1: Recall unit conversion
We know that $ 1 \text{ meter} = 100 \text{ centimeters} $, so to convert centimeters to meters, we divide by 100.
## Step2: Perform the conversion
For $ 8.72 $ centimeters, the conversion to meters is $ 8.72\div100 = 0.0872 $ meters.
# Answer:
b. 0.0872

### Question 16
# Brief Explanations:
Malleability is the property of a metal to be pounded or rolled into thin sheets. Solubility is about dissolving, ductility is about drawing into wires, and electromagnetism is about magnetic and electric fields.
# Answer:
b. Malleability

### Question 17
# Brief Explanations:
A physical change is a change that does not alter the chemical composition. Cutting paper only changes its shape, while burning wood, dying hair, and leaves changing color involve chemical reactions (new substances formed).
# Answer:
d. Cutting a piece of paper during art class

### Question 18
# Brief Explanations:
Burning wood (combustion, new substances), dying hair (chemical reaction with hair and dye), and leaves changing color (chlorophyll breakdown, new pigments) are all chemical changes as they form new substances. So all of the above are chemical changes.
# Answer:
d. All of the above

### Question 19
# Brief Explanations:
A salad has different components (lettuce, tomatoes, etc.) that are not uniformly distributed, so it's a heterogeneous mixture. Homogeneous mixtures are uniform, compounds and elements are pure substances, not mixtures.
# Answer:
b. Heterogeneous mixture

### Question 20
# Brief Explanations:
$ \text{NaCl} $ (sodium chloride) is made of two different elements (sodium and chlorine) chemically bonded, so it's a compound. Mixtures have multiple substances without chemical bonding, and elements are single types of atoms.
# Answer:
c. Compound

### Question 21 (assuming options are about element, compound, mixture; typical classification: Nitrogen is $ \text{N}_2 $, a diatomic molecule of the element nitrogen, so it's an element)
# Brief Explanations:
Nitrogen ($ \text{N}_2 $) is a pure substance made of only nitrogen atoms, so it's an element. Compounds have multiple elements, mixtures have multiple substances.
# Answer:
(Assuming options include "Element") d. Element (or the option corresponding to Element)

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QUESTION IMAGE

Question

Explanation:

Question 15

Step1: Recall unit conversion

Step2: Perform the conversion

Answer:

Question 16