Q: Which of the following is the correct relationship for the calculation of density?

$$\text{Density} = \frac{\text{mass}}{\text{volume}}$$

Q: Which of the following is the correct formula for calculating the percentage of a value relative to a total?

$$\frac{\text{part}}{\text{total}} \times 100\%$$

Q: Which of the following is the correct logarithmic relationship for pH?

$$\text{pH} = -\log_{10}[H^+]$$

Question 1

Which of the following best describes the difference between precision and accuracy in chemical measurements?

Accepted Answer

Precision refers to how close repeated measurements are to each other, while accuracy refers to how close a measured value is to the true value.

Question 2

A student measures the mass of a sample four times and records: 4.12 g, 4.13 g, 4.11 g, and 4.12 g. The true mass is 4.50 g. Which statement is correct?

Accepted Answer

The measurements are precise but not accurate.

Question 3

How many significant figures are in the number 0.004520?

Accepted Answer

4

Question 4

Which of the following is the correct scientific notation for 0.000378?

Accepted Answer

$$3.78 	imes 10$$^{-4}$$

Question 5

A nutrition label states that a serving of yogurt provides 418 kJ of energy. If the recommended daily intake is 8700 kJ, what percentage of the daily intake does one serving provide?

Accepted Answer

$$4.8\%$$

Question 6

Which of the following is NOT an SI base unit?

Accepted Answer

liter

Question 7

Convert $$2.5 	imes 10^3$ milligrams to grams.

Accepted Answer

$$2.5$$ grams

Question 8

Which of the following correctly expresses the result of $$6.02 	imes 10$$^{23}$$ \div 3.01 	imes 10$$^{22}$$ in scientific notation?

Accepted Answer

$$2.0 	imes 10^1$

Question 9

A solution has a concentration of $$0.015$$ mol/L. If you dilute it to $$0.005$$ mol/L, by what factor has the concentration decreased?

Accepted Answer

By a factor of 3

Question 10

Which of the following is the correct relationship for the calculation of density?

Accepted Answer

$$	ext{Density} = \frac{	ext{mass}}{	ext{volume}}$$

Question 11

A graph of absorbance versus concentration of ions in solution is linear. What does this indicate about the relationship between absorbance and concentration?

Accepted Answer

Absorbance is directly proportional to concentration.

Question 12

If the pH of a solution is 3, what is the concentration of $$[H^+] in $$mol/L?

Accepted Answer

$$1 	imes 10$$^{-3}$$ mol/L

Question 13

Which of the following is the correct rule for determining the number of significant figures in the number 0.02030?

Accepted Answer

Zeros to the right of a decimal point and after a nonzero digit are significant.

Question 14

A student needs to convert 5.0 km to meters using SI prefixes. What is the correct answer?

Accepted Answer

$$5.0 	imes 10^3$ m

Question 15

Which of the following best describes dimensional analysis?

Accepted Answer

A process for converting between units using conversion factors.

Question 16

If a measurement is reported as $$2.30 	imes 10^2$ g, how many significant figures does it have?

Accepted Answer

3

Question 17

Which of the following is the correct formula for calculating the percentage of a value relative to a total?

Accepted Answer

$$\frac{	ext{part}}{	ext{total}} 	imes 100\%$$

Question 18

A solution is prepared by dissolving 5.0 g of salt in enough water to make 250 mL of solution. What is the concentration in g/L?

Accepted Answer

$$20 g/L$$

Question 19

Which of the following is the correct logarithmic relationship for pH?

Accepted Answer

$$	ext{pH} = -\log_{10}[H^+]$$

Measurement and Chemical Calculations: Essential Skills for General Chemistry

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