Q: Which of the following is the correct formula for density?

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

Question 1

Which of the following best describes the metric system?

Accepted Answer

A unified and rational system that uses prefixes to indicate size and is based on powers of 10

Question 2

Which SI prefix corresponds to a multiplier of $$10^{-6}$$?

Accepted Answer

micro

Question 3

A student measures the length of a pencil as 12.30 cm using a ruler with the smallest division of 0.1 cm. What is the uncertainty of this measurement?

Accepted Answer

$$\pm 0.05 cm$$

Question 4

How many significant figures are in the measurement 0.02050 kg?

Accepted Answer

4

Question 5

When multiplying $$2.30 	imes 1.002$$, how many significant figures should the final answer have?

Accepted Answer

3

Question 6

A graduated cylinder contains water up to the 25.0 mL mark. If you add a rock and the water rises to 32.5 mL, what is the volume of the rock, and how many significant figures should your answer have?

Accepted Answer

7.5 mL, 3 significant figures

Question 7

Convert 3.0 miles to inches. (1 mile = 5280 ft, 1 ft = 12 in). Express your answer in scientific notation with the correct number of significant figures.

Accepted Answer

$$1.8 	imes 10^5$ in

Question 8

Which of the following is the correct way to count significant figures in the number 0.004560?

Accepted Answer

Count all digits except leading zeros; answer is 4

Question 9

A copper block has a mass of 150.8 g and a volume of 17.0 mL. What is its density, and how many significant figures should the answer have?

Accepted Answer

$$8.87 g/mL$$, 3 significant figures

Question 10

Which of the following best explains why the mole is a special counting unit in chemistry?

Accepted Answer

It is the number of atoms in 12 grams of carbon-12

Question 11

How many atoms are in 2.0 moles of carbon?

Accepted Answer

$$1.2 	imes 10$$^{24}$$ atoms

Question 12

What is the mass of 2 moles of helium (He)? (Atomic mass of He = 4.00 g/mol)

Accepted Answer

8 g

Question 13

Which of the following is the correct formula for density?

Accepted Answer

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

Question 14

If you want to calculate the largest possible density from a set of measurements, which values should you use?

Accepted Answer

Largest mass and smallest volume

Question 15

Which of the following measurements is the most precise?

Accepted Answer

150.8 g

Question 16

A student records a measurement as $$2.55 mL. $$According to the rules for significant figures, what does the last digit (5) represent?

Accepted Answer

An estimated digit, representing uncertainty

Question 17

Which of the following is the correct way to express 210,000 in scientific notation with the correct number of significant figures if the original measurement was 2.1 x $$10^5$$?

Accepted Answer

$$2.1 	imes 10^5$

Question 18

When adding $$2.45$$ and $$2.8$$, what is the correct answer with the proper number of decimal places?

Accepted Answer

$$5.3$$

Question 19

Which of the following is NOT a base SI unit?

Accepted Answer

Gram

Question 20

A sample of diatomic oxygen ($$O_2) $$has a mass of 32.00 g. How many moles of $$O_2$$ are present?

Accepted Answer

1.00 mol

Introduction to Chemistry: Measurement, Units, and the Mole Concept

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