Question 1

A student measures the mass of a sample before and after a chemical reaction in a closed system. The mass remains unchanged. Which law does this observation best illustrate?

Accepted Answer

Law of Conservation of Mass

Question 2

Which of the following best describes a chemical change?

Accepted Answer

Iron rusting in moist air

Question 3

A sample of gold has a mass of $$19.3\ \mathrm{g}$$ and a volume of $$1.00\ \mathrm{cm}^3. $$What is the density of gold in $$\mathrm{g/cm}^3$$?

Accepted Answer

$$19.3\ \mathrm{g/cm}^3$$

Question 4

Which of the following is a heterogeneous mixture?

Accepted Answer

Salad with lettuce, tomatoes, and cucumbers

Question 5

A student records the following measurements: $$2.50\ \mathrm{g}$$, $$2.5\ \mathrm{g}$$, $$2.500\ \mathrm{g}$$, and $$2.5000\ \mathrm{g}. $$Which measurement has the greatest number of significant figures?

Accepted Answer

$$2.5000\ \mathrm{g}$$

Question 6

Convert $$5.00\ \mathrm{km} to $$meters using dimensional analysis.

Accepted Answer

$$5000\ \mathrm{m}$$

Question 7

Which of the following statements about isotopes is correct?

Accepted Answer

Isotopes of an element have the same number of protons but different numbers of neutrons.

Question 8

Which of the following is the correct scientific notation for $$0.000345$$?

Accepted Answer

$$3.45 	imes 10$$^{-4}$$

Question 9

A sample contains $$80\%$$ $$^{35}\mathrm{Cl} ($$atomic mass $$34.97 u) $$and $$20\%$$ $$^{37}\mathrm{Cl} ($$atomic mass $$36.97 u). $$What is the average atomic mass of chlorine?

Accepted Answer

$$35.37 u$$

Question 10

Which of the following is NOT a step in the scientific method?

Accepted Answer

Ignoring experimental results

Question 11

Which of the following best describes the structure of an atom?

Accepted Answer

A dense nucleus containing protons and neutrons, surrounded by electrons in a cloud

Question 12

Which of the following is a physical change?

Accepted Answer

Dissolving sugar in water

Question 13

Which prefix represents $$10^{-9}$$?

Accepted Answer

nano-

Question 14

Which of the following elements is a noble gas?

Accepted Answer

Neon ($$\mathrm{Ne})$$

Question 15

A block of metal has a mass of $$54.0\ \mathrm{g}$$ and a volume of $$18.0\ \mathrm{cm}^3. $$What is its density?

Accepted Answer

$$3.00\ \mathrm{g/cm}^3$$

Question 16

Which of the following best describes a homogeneous mixture?

Accepted Answer

A mixture with uniform composition throughout

Question 17

Which of the following statements about the periodic table is correct?

Accepted Answer

Elements in the same group have similar chemical properties

Question 18

A student needs to convert $$250\ \mathrm{mg} to $$grams. What is the correct value?

Accepted Answer

$$0.25\ \mathrm{g}$$

Question 19

Which of the following is the correct number of significant figures in the measurement $$0.00450$$?

Accepted Answer

3

Question 20

Which of the following best explains why mass is conserved in a chemical reaction?

Accepted Answer

Atoms are rearranged but not created or destroyed during a chemical reaction

Fundamental Concepts in General Chemistry: Measurement, Matter, and Atomic Structure

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