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 correct value in Newton·seconds, what is the correct value in Newton·seconds? (1 pound = 4.44822 N)

$$50.0 \times 4.44822 = 222$$ Newton\cdot seconds

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

$$21.5 \times 4.49 = 96.5\ \mathrm{g}$$

Q: A motorcycle is traveling at $$105 km/h. $$What is its speed in meters per second? ($$1 km$$ $$= 1000 m$$, $$1 h$$ $$= 3600 s)$$

$$105 \times \frac{1000}{3600} = 29.2 m/s$$

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

$$^\circ F = 1.8 \times (^\circ C) + 32$$

Q: A student needs to convert $$5.70 in$^3 to cm$^3$$. ($$1 in$$ $$= 2.54 cm)$$

$$5.70 \times (2.54)^3$ = 93.4 cm$^3$$

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 correct value in Newton·seconds, what is the correct value in Newton·seconds? (1 pound = 4.44822 N)

Accepted Answer

$$50.0 	imes 4.44822 = 222$$ Newton\cdot seconds

Question 2

Which of the following numbers has exactly three significant figures?

Accepted Answer

$$0.0340$$

Question 3

A student measures the mass of a sample as $$2.50 g $$and its volume as $$1.25 mL. $$What is the density of the sample, and how many significant figures should the answer have?

Accepted Answer

$$2.00 g/mL$$, 3 significant figures

Question 4

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

Accepted Answer

$$25.0 + 273.15 = 298.15\ \mathrm{K}$$

Question 5

Which of the following statements about significant figures is correct?

Accepted Answer

Zeros between nonzero digits are always significant.

Question 6

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

Accepted Answer

$$21.5 	imes 4.49 = 96.5\ \mathrm{g}$$

Question 7

Which of the following is an example of an intensive property?

Accepted Answer

Density

Question 8

A student records the following measurements: $$6.64$$, $$6.68$$, and $$6.70 cm. $$What is the average, and how many significant figures should it be reported with?

Accepted Answer

$$6.67 cm$$, 3 significant figures

Question 9

Convert $$1516 g to $$kilograms using dimensional analysis.

Accepted Answer

$$1516 \div 1000 = 1.516 kg$$

Question 10

A motorcycle is traveling at $$105 km/h. $$What is its speed in meters per second? ($$1 km$$ $$= 1000 m$$, $$1 h$$ $$= 3600 s)$$

Accepted Answer

$$105 	imes \frac{1000}{3600} = 29.2 m/s$$

Question 11

Which of the following is the correct scientific notation for the number $$0.0000000000000000000000199$$?

Accepted Answer

$$1.99 	imes 10$$^{-23}$$

Question 12

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

Accepted Answer

$$^\circ F = 1.8 	imes (^\circ C) + 32$$

Question 13

A sample of mercury has a density of $$13.6\ \mathrm{g/cm}^3. $$What is the mass of $$95 mL of $$mercury? ($$1 mL$$ $$= 1 cm$^3)$$

Accepted Answer

$$13.6 	imes 95 = 1292 g$$

Question 14

Which of the following is NOT a base SI unit?

Accepted Answer

Liter (L)

Question 15

Which of the following is the correct prefix and symbol for $$10^{-6}$$?

Accepted Answer

micro, $$\mu$$

Question 16

A student needs to convert $$5.70 in$^3 to cm$^3$$. ($$1 in$$ $$= 2.54 cm)$$

Accepted Answer

$$5.70 	imes (2.54)^3$ = 93.4 cm$^3$$

Question 17

Which of the following best describes an exothermic process?

Accepted Answer

Heat transfers from the system to the surroundings, and the temperature of the surroundings increases.

Question 18

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

Accepted Answer

6

Question 19

Which of the following is the correct equation for kinetic energy?

Accepted Answer

$$KE = \frac{1}{2}mv^2$

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

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