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

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

Q: A patient’s body temperature is measured as $$39.0\ ^\circ C. $$What is this temperature in Fahrenheit?

$$1.8 \times 39.0 + 32 = 102.2\ ^\circ F$$

Q: Which of the following conversions is correct for $$1.516 kg to $$grams?

$$1.516 \times 1000 = 1516\ g$$

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

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

Q: A solution has a density of $$0.768\ g/cm^3$ and a volume of 1732.31$$\ L$$. What is the mass in kilograms? (1$$\ L = 1000\ $$cm^3)$$

$$0.768 \times 1732.31 \times 1000 \div 1000 = 1330\ kg$$

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, 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

$$0.0300$$

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

$$2.7$$ \frac{g}{mL}$

Question 4

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

Accepted Answer

$$25.0 + 273.15 = 298.15\ K$$

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 $$21.5\ g/cm^3$ and a volume of 4.49$$\ $$cm^3. $$What is its mass?

Accepted Answer

$$21.5 	imes 4.49 = 96.5\ g$$

Question 7

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

Accepted Answer

Density

Question 8

A patient’s body temperature is measured as $$39.0\ ^\circ C. $$What is this temperature in Fahrenheit?

Accepted Answer

$$1.8 	imes 39.0 + 32 = 102.2\ ^\circ F$$

Question 9

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

Accepted Answer

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

Question 10

A sample of mercury has a mass of $$1292 g $$and a volume of $$95.0 mL. $$What is the density of mercury in $$g/cm^3$$?

Accepted Answer

$$1292 \div 95.0 = 13.6\ g/cm^3$

Question 11

Which of the following conversions is correct for $$1.516 kg to $$grams?

Accepted Answer

$$1.516 	imes 1000 = 1516\ g$$

Question 12

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

Accepted Answer

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

Question 13

Which of the following best describes an exothermic process?

Accepted Answer

Heat flows from the system to the surroundings, increasing the temperature of the surroundings.

Question 14

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

Accepted Answer

6

Question 15

Which of the following is the correct relationship for converting calories to joules?

Accepted Answer

$$1\ cal = 4.184\ J$$

Question 16

A solution has a density of $$0.768\ g/cm^3$ and a volume of 1732.31$$\ L$$. What is the mass in kilograms? (1$$\ L = 1000\ $$cm^3)$$

Accepted Answer

$$0.768 	imes 1732.31 	imes 1000 \div 1000 = 1330\ kg$$

Question 17

Which of the following is the correct SI base unit for luminous intensity?

Accepted Answer

Candela (cd)

Question 18

A $$325 mg $$aspirin tablet has what mass in grams?

Accepted Answer

$$325 \div 1000 = 0.325\ g$$

Question 19

Which of the following is the correct scientific notation for the number $$6,022,000,000,000,000,000,000,000$$?

Accepted Answer

$$6.022 	imes 10$$^{23}$$

Essentials: Units, Measurements, and Problem Solving in General Chemistry

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