Question 1

Which of the following best describes the difference between a scientific law and a scientific theory?

Accepted Answer

A law summarizes a series of related observations, while a theory gives the underlying reasons for them.

Question 2

Which of the following is an example of a chemical property?

Accepted Answer

Flammability

Question 3

A sample of water is heated and changes from liquid to gas. Which type of change is this?

Accepted Answer

Physical change

Question 4

Which statement correctly applies the law of conservation of mass to a chemical reaction?

Accepted Answer

The total mass of substances involved in the reaction does not change.

Question 5

Which of the following is a homogeneous mixture?

Accepted Answer

Salt dissolved in water

Question 6

Which of the following statements is NOT part of Dalton’s atomic theory?

Accepted Answer

Atoms can be created or destroyed in chemical reactions.

Question 7

A nuclide has 28 protons and 31 neutrons. What is the correct isotope symbol for this atom?

Accepted Answer

$$^{59}_{28}Ni$$

Question 8

Which subatomic particle has a mass of approximately $$1.00866$$ amu and no charge?

Accepted Answer

Neutron

Question 9

Copper has two naturally occurring isotopes: copper-63 (69.15%, 62.93 amu) and copper-65 (30.85%, 64.93 amu). What is the atomic mass of copper?

Accepted Answer

$$63.55$$ amu

Question 10

A neutral atom of $$^{80}_{35}Br$$ has how many protons, neutrons, and electrons?

Accepted Answer

35 protons, 45 neutrons, 35 electrons

Question 11

Chlorine has two main isotopes: $$^{35}Cl$$ and $$^{37}Cl. $$What is the number of neutrons in each isotope?

Accepted Answer

$$^{35}Cl$$: 18 neutrons; $$^{37}Cl$$: 20 neutrons

Question 12

Which of the following best describes an extensive property?

Accepted Answer

A property that varies with the amount of the substance present

Question 13

How many moles of potassium atoms are present in $$19.5 g of $$potassium? (Molar mass of K = $$39.10 g/$$mol)

Accepted Answer

$$0.499$$ mol

Question 14

A sample contains $$3.737 	imes 10$$^{22}$$ sodium atoms. How many moles of sodium atoms are present? (N_A = 6.022$$ 	imes $$10^{23}$$ mol$$^{-1})$$

Accepted Answer

$$0.0620$$ mol

Question 15

Which of the following is a pure substance?

Accepted Answer

Oxygen gas ($$O_2)$$

Question 16

Which experiment led to the discovery of the nucleus in the atom?

Accepted Answer

Rutherford’s gold foil experiment

Question 17

Which of the following best describes the law of definite proportions?

Accepted Answer

All samples of a compound contain the same elements in the same proportions by mass.

Question 18

Which of the following is the correct value for Avogadro’s number?

Accepted Answer

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

Question 19

A sample contains $$51 g of $$titanium (Ti). How many moles of Ti are present? (Molar mass of Ti = $$47.87 g/$$mol)

Accepted Answer

$$1.07$$ mol

Question 20

Which of the following statements about ions is correct?

Accepted Answer

Cations are positively charged ions formed by metals.

Atoms and the Foundations of Chemistry: Structure, Properties, and Classification of Matter

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