Q: A NASA spacecraft was lost due to a unit conversion error between metric and English units. If a force was entered as 50.0 pound·seconds instead of the required Newton·seconds, and 1 pound = 4.44822 Newtons, what was the force in Newton·seconds that should have been entered?

$$222.4 \\ \text{Newton·seconds}$$

Q: Which of the following conversion factors is NOT correct?

$$1 \\ \text{km} = 100 \\ \text{m}$$

Q: Which of the following is the correct relationship for converting Celsius to Fahrenheit?

$$^{\circ}F = 1.8 \\$$times ^{\circ}$$C + 32$$

Question 1

A NASA spacecraft was lost due to a unit conversion error between metric and English units. If a force was entered as 50.0 pound·seconds instead of the required Newton·seconds, and 1 pound = 4.44822 Newtons, what was the force in Newton·seconds that should have been entered?

Accepted Answer

$$222.4 \ 	ext{Newton·seconds}$$

Question 2

Which of the following numbers has exactly three significant figures?

Accepted Answer

$$0.304$$

Question 3

A student measures the mass of a sample as $$12.30 g $$and its volume as $$4.5 mL. $$What is the density of the sample, reported with the correct number of significant figures?

Accepted Answer

$$2.7 \ 	ext{g/mL}$$

Question 4

Which of the following statements about intensive and extensive properties is correct?

Accepted Answer

Density is an intensive property because it does not depend on the amount of substance.

Question 5

Convert a temperature of $$25.0^{\circ}C$ to Kelvin.

Accepted Answer

$$298.15 \ 	ext{K}$$

Question 6

A sample of gold has a mass of $$19.3 g $$and a volume of $$1.00 cm$^3. $$What is the density of gold in kg/m$$^3$$?

Accepted Answer

$$19,300 \ 	ext{kg/m}^3$$

Question 7

Which of the following is the correct scientific notation for the number $$0.000420$$ with the correct number of significant figures?

Accepted Answer

$$4.20 \ 	imes 10$$^{-4}$$

Question 8

A patient’s body temperature is measured as $$102.2^{\circ}F$. What is this temperature in Celsius?

Accepted Answer

$$39.0^{\circ}C$

Question 9

Which of the following conversion factors is NOT correct?

Accepted Answer

$$1 \ 	ext{km} = 100 \ 	ext{m}$$

Question 10

A car is traveling at $$60.0$$ miles per hour. What is its speed in meters per second? ($$1 \ 	ext{mile} = 1609 \ 	ext{m}$$, $$1 \ 	ext{hour} = 3600 \ 	ext{s})$$

Accepted Answer

$$26.8 \ 	ext{m/s}$$

Question 11

Which of the following best describes the First Law of Thermodynamics?

Accepted Answer

Energy cannot be created or destroyed, only converted from one form to another.

Question 12

A sample of mercury has a density of $$13.6 \ 	ext{g/cm}^3. $$What is the mass in grams of $$50.0 mL of $$mercury? ($$1 \ 	ext{mL} = 1 \ 	ext{cm}^3)$$

Accepted Answer

$$680 \ 	ext{g}$$

Question 13

Which of the following is an example of an exact number in chemistry?

Accepted Answer

The number of centimeters in a meter

Question 14

A student records the following measurements: $$2.45 m$$, $$2.4 m$$, and $$2.47 m. $$The true value is $$2.46 m. $$Which statement best describes the accuracy and precision of these measurements?

Accepted Answer

The measurements are both accurate and precise.

Question 15

Which of the following numbers has four significant figures?

Accepted Answer

$$0.01200$$

Question 16

A piece of platinum metal has a density of $$21.5 \ 	ext{g/cm}^3$$ and a volume of $$4.49 \ 	ext{cm}^3. $$What is its mass?

Accepted Answer

$$96.5 \ 	ext{g}$$

Question 17

Which of the following is the correct relationship for converting Celsius to Fahrenheit?

Accepted Answer

$$^{\circ}F = 1.8 \$$times ^{\circ}$$C + 32$$

Question 18

A $$325 mg $$aspirin tablet has a mass of how many grams?

Accepted Answer

$$0.325 \ 	ext{g}$$

Question 19

Which of the following best describes an endothermic process?

Accepted Answer

Heat flows from the surroundings into the system, increasing the system's energy.

Question 20

How many significant figures are in the number $$0.00801008$$?

Accepted Answer

6

Essentials of Units, Measurement, and Problem Solving in General Chemistry

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