Q: A sample of white gold is made of 18.0 g gold, 3.0 g silver, 2.0 g cobalt, and 1.0 g platinum. What is the percent platinum in the sample?

$$\frac{1.0}{24.0} \times 100\% = 4.2\%$$

Q: If a 5¢ coin has a mass of 5.07 g and is 25.0% nickel, what is the mass of nickel in the coin?

$$0.25 \times 5.07\,\mathrm{g} = 1.27\,\mathrm{g}$$

Q: The density of alcohol is $$0.813\,\mathrm{g/mL}. $$How many grams of alcohol are present in a $$250.0\,\mathrm{mL}$$ sample?

$$0.813 \times 250.0 = 203\,\mathrm{g}$$

Q: A swimming pool holds $$76.0$$ gallons of water. If you have a $$1.00$$ liter bucket, how many buckets do you need to fill the pool? ($$1$$ gallon $$= 3.785 L)$$

$$76.0 \times 3.785 = 287.6$$ buckets, rounded to $$288$$

Q: A car travels $$455$$ miles at an average speed of $$57.5$$ miles per hour. How long (in minutes) will it take to reach the destination?

$$\frac{455}{57.5} \times 60 = 474.7$$ minutes, rounded to $$475$$ minutes

Q: What is the value of Avogadro's constant, and how many significant figures does it have in the value $$6.022140857 \times 10$$^{23}$$?

$$6.022140857 \times 10$$^{23}$$, 12 significant figures

Q: Which of the following is the correct value and unit for the elementary charge?

$$1.602 \times 10$$^{-19}$$\,\mathrm{C}$$

Question 1

Which of the following is the correct term for the metric unit of length?

Accepted Answer

meter

Question 2

What is the term for the smallest particle that represents an element?

Accepted Answer

Atom

Question 3

How many significant figures are in the value $$6.022140857 	imes 10$$^{23}$$?

Accepted Answer

12

Question 4

Which of the following correctly expresses $$9.00 	imes 10$$^{7}$$ in decimal form?

Accepted Answer

$$90000000$$

Question 5

A sample of white gold is made of 18.0 g gold, 3.0 g silver, 2.0 g cobalt, and 1.0 g platinum. What is the percent platinum in the sample?

Accepted Answer

$$\frac{1.0}{24.0} 	imes 100\% = 4.2\%$$

Question 6

If a 5¢ coin has a mass of 5.07 g and is 25.0% nickel, what is the mass of nickel in the coin?

Accepted Answer

$$0.25 	imes 5.07\,\mathrm{g} = 1.27\,\mathrm{g}$$

Question 7

The density of alcohol is $$0.813\,\mathrm{g/mL}. $$How many grams of alcohol are present in a $$250.0\,\mathrm{mL}$$ sample?

Accepted Answer

$$0.813 	imes 250.0 = 203\,\mathrm{g}$$

Question 8

A swimming pool holds $$76.0$$ gallons of water. If you have a $$1.00$$ liter bucket, how many buckets do you need to fill the pool? ($$1$$ gallon $$= 3.785 L)$$

Accepted Answer

$$76.0 	imes 3.785 = 287.6$$ buckets, rounded to $$288$$

Question 9

Convert $$123.8^\circ\mathrm{F} to $$Kelvin. ($$^\circ\mathrm{C} = \frac{5}{9}(F - 32)$$, $$K = ^\circ\mathrm{C} + 273.15)$$

Accepted Answer

$$^\circ\mathrm{C} = \frac{123.8 - 32}{1.8} = 51^\circ\mathrm{C}$$, $$K = 51 + 273.15 = 324.15 K$$

Question 10

A car travels $$455$$ miles at an average speed of $$57.5$$ miles per hour. How long (in minutes) will it take to reach the destination?

Accepted Answer

$$\frac{455}{57.5} 	imes 60 = 474.7$$ minutes, rounded to $$475$$ minutes

Question 11

Which of the following is the correct symbol and multiple for the prefix 'giga-'?

Accepted Answer

G, $$1,000,000,000$$

Question 12

Which of the following measurements is correctly reported to the proper number of significant figures?

Accepted Answer

$$2.35\,\mathrm{cm}$$

Question 13

What is the value of Avogadro's constant, and how many significant figures does it have in the value $$6.022140857 	imes 10$$^{23}$$?

Accepted Answer

$$6.022140857 	imes 10$$^{23}$$, 12 significant figures

Question 14

Which of the following is the correct formula for density?

Accepted Answer

$$D = \frac{m}{V}$$

Question 15

Which of the following is the correct scientific notation for the speed of light, $$299,800,000 m/s$$?

Accepted Answer

$$2.998 	imes 10$$^{8}$$ m/s

Question 16

Which of the following is the correct decimal form of $$2.574 	imes 10$$^{7}$$?

Accepted Answer

$$25740000$$

Question 17

A grain of sugar weighs approximately $$0.0000625 g. $$How many significant figures does this value have?

Accepted Answer

3

Question 18

Which of the following is the correct value and unit for the elementary charge?

Accepted Answer

$$1.602 	imes 10$$^{-19}$$\,\mathrm{C}$$

Introduction to Chemistry: Measurement, Significant Figures, and Unit Conversions

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