Q: Which of the following conversion factors would you use to convert meters to kilometers?

$\frac{1 \text{ km}}{1000 \text{ m}}$

Q: A solution contains $32$ mg/mL of a drug. What is this concentration in g/L?

$32$ mg/mL \times \frac{1 \text{ g}}{1000 \text{ mg}} \times 1000 \text{ mL}/1 \text{ L} = 32$ g/L

Q: When converting $5.0$ in$^2$ to cm$^2$, which conversion factor should be used?

$\left(\frac{2.54 \text{ cm}}{1 \text{ in}}\right)^2$

Question 1

Which of the following numbers is correctly expressed in scientific notation?

Accepted Answer

$5.2 	imes 10^3$

Question 2

A laboratory balance shows a mass reading of 12.30 g. Which statement best describes the certainty of this measurement?

Accepted Answer

The last digit (0) is estimated and indicates uncertainty.

Question 3

Express the number 0.000456 in scientific notation.

Accepted Answer

$4.56 	imes 10^{-4}$

Question 4

How many significant figures are in the measurement 0.00450 m?

Accepted Answer

3

Question 5

Which of the following is an exact number?

Accepted Answer

The number of students in a classroom

Question 6

A student multiplies $2.34$ (3 sig figs) by $0.056$ (2 sig figs) and gets $0.13104$. According to the rules for significant figures, what should the answer be reported as?

Accepted Answer

$0.13$

Question 7

Which of the following correctly describes the difference between mass and weight?

Accepted Answer

Mass is a measure of matter, weight is a measure of gravitational pull.

Question 8

Convert $5.67 	imes 10^3$ mg to grams using scientific notation.

Accepted Answer

$5.67$ g

Question 9

A car is traveling at $90$ km/hr. What is its speed in m/s? ($1$ km = $1000$ m, $1$ hr = $3600$ s)

Accepted Answer

$25$ m/s

Question 10

Which SI base units correspond to length, mass, and time, respectively?

Accepted Answer

meter, kilogram, second

Question 11

A sample of an unknown metal has a mass of $31.5$ g and a volume of $3.11$ cm$^3$. What is its density?

Accepted Answer

$10.1$ g/cm$^3$

Question 12

Which of the following conversion factors would you use to convert meters to kilometers?

Accepted Answer

$\frac{1 	ext{ km}}{1000 	ext{ m}}$

Question 13

A classroom has a volume of $285$ m$^3$. What is this volume in cm$^3$? ($1$ m = $100$ cm$)$

Accepted Answer

$2.85 	imes 10^8$ cm$^3$

Question 14

A solution contains $32$ mg/mL of a drug. What is this concentration in g/L?

Accepted Answer

$32$ mg/mL 	imes \frac{1 	ext{ g}}{1000 	ext{ mg}} 	imes 1000 	ext{ mL}/1 	ext{ L} = 32$ g/L

Question 15

A drop of acetone has a mass of $35$ mg and a density of $0.788$ g/cm$^3$. What is its volume in cm$^3$?

Accepted Answer

$0.044$ cm$^3$

Question 16

When converting $5.0$ in$^2$ to cm$^2$, which conversion factor should be used?

Accepted Answer

$\left(\frac{2.54 	ext{ cm}}{1 	ext{ in}}ight)^2$

Question 17

A calculation involves the following steps: $(4.56 + 1.2) 	imes 3.45$. According to significant figure rules, how many significant figures should the final answer have?

Accepted Answer

2

Question 18

Which of the following is the most appropriate SI prefix to express the length of a typical chemical bond ($1.2 	imes 10^{-10}$ m)?

Accepted Answer

pico-

Question 19

A metal cylinder has a volume of $246$ cm$^3$ and a density of $7.93$ g/cm$^3$. What is its mass in grams?

Accepted Answer

$1950$ g

Measurement and Problem Solving in Chemistry: Scientific Notation and Uncertainty

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