13. you are conducting an experiment and find the volume of a substance to be 9.85 ml. if the known volume of the substance is 10.25 ml, find the percentage error in your measurement.
a. -3.90%
b. -4.06%
c. 3.90%
d. 4.06%
14. a factor in an experiment that is kept the same amongst all groups in an experiment is the
a. control group
b. independent variable
c. constant
d. dependent variable
15. how many significant figures are in the speed of light, 3.0×10^8 m/s?
a. 0
b. 2
c. 5
d. 8
16. which of the following is not a sign that a chemical reaction may have occurred?
a. sudden color change from clear to yellow
b. changing state from liquid to gas
c. the formation of a precipitate
d. giving off heat
17. four different liquids (syrup, water, motor oil, and alcohol) are spilled at the same time on an inclined plane. the data table to the right shows the time it took each to reach the bottom of the plane. based on the data table, which liquid is most likely the most viscous?
a. syrup
b. water
c. motor oil
d. alcohol
18. what is purposefully being manipulated and changed in an experiment is the
a. control group
b. independent variable
c. constant
d. dependent variable
19. calcium chloride has a density of 2.50 g/cm³. if you have 218 g of it, what volume do you have?
a. 87.2 cm³
b. 545 cm³
c. 87.2 g
d. 545 g
which of the following statements about a chemical change is true?
a. a chemical change results in a change in energy but not a change in the amount of matter.
b. a chemical change results in a change in the amount of matter but not a change in energy.
c. a chemical change results in a change in energy or a change in the amount of matter.
d. a chemical change results in a change in energy and a change in the amount of matter.

Question

Accepted Answer

13.
# Explanation:
## Step1: Recall percentage - error formula
The formula for percentage error is $\text{Percentage Error}=\frac{\vert\text{Measured Value}-\text{True Value}\vert}{\text{True Value}}\times100\%$. The measured value is $9.85$ mL and the true value is $10.25$ mL.
$$
\begin{align*}
\text{Percentage Error}&=\frac{\vert9.85 - 10.25\vert}{10.25}\times100\%\
&=\frac{\vert - 0.4\vert}{10.25}\times100\%\
&=\frac{0.4}{10.25}\times100\%\
&\approx3.90\%
\end{align*}
$$
# Answer:
C. 3.90%

14.
# Brief Explanations:
A factor that is kept the same amongst all groups in an experiment is a constant. A control group is a group that is not manipulated. An independent variable is the variable that is being manipulated, and a dependent variable is the variable that changes as a result of the independent - variable.
# Answer:
C. constant

15.
# Brief Explanations:
The speed of light is $3.0\times10^{8}$ m/s. The significant figures are the digits that carry meaningful information about the precision of a measurement. In $3.0\times10^{8}$, the significant figures are 2 (the 3 and the 0).
# Answer:
B. 2

16.
# Brief Explanations:
A sudden color change, formation of a precipitate, and giving off heat are signs of a chemical reaction. Changing state from liquid to gas is a physical change (evaporation).
# Answer:
B. Changing state from liquid to gas

17.
# Brief Explanations:
Viscous liquids flow more slowly. Syrup is generally the most viscous among syrup, water, motor - oil, and alcohol. The liquid that takes the most time to reach the bottom of an inclined plane is the most viscous.
# Answer:
A. Syrup

18.
# Brief Explanations:
The variable that is purposefully being manipulated in an experiment is the independent variable. A control group is a non - manipulated group, a constant is a factor that is kept the same, and a dependent variable changes as a result of the independent variable.
# Answer:
B. independent variable

19.
# Explanation:
## Step1: Recall density formula
The density formula is $
ho=\frac{m}{V}$, where $
ho$ is density, $m$ is mass, and $V$ is volume. We need to solve for $V$, so $V = \frac{m}{
ho}$. Given $m = 218$ g and $
ho=2.50$ g/cm³.
$$
V=\frac{218\text{ g}}{2.50\text{ g/cm³}} = 87.2\text{ cm³}
$$
# Answer:
A. 87.2 cm³

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QUESTION IMAGE

Question

Explanation:

Step1: Recall percentage - error formula

Answer: