Q: A copper penny has a mass of 3.10 grams. How many copper atoms does it contain? (Molar mass of Cu = $$63.55\ \mathrm{g/mol}$$, $$N_A = 6.022 \times 10$$^{23}$$)

$$2.94 \times 10$$^{22}$$ atoms

Question 1

Which of the following best describes the difference between a compound and a mixture?

Accepted Answer

A compound is made of two or more elements in fixed, definite proportions, while a mixture is composed of two or more substances in variable proportions.

Question 2

Which experiment provided evidence for the existence of the electron as a negatively charged particle present in all atoms?

Accepted Answer

J.J. Thomson's cathode ray experiment

Question 3

A sample of water is decomposed into 16.0 g of oxygen and 2.0 g of hydrogen. What law does this observation support?

Accepted Answer

Law of definite proportions

Question 4

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 5

A neutral atom of chlorine has 17 protons and 18 neutrons. What is the isotope symbol for this atom?

Accepted Answer

$$^{35}_{17}\mathrm{Cl}$$

Question 6

Which of the following is a real-world example of a homogeneous mixture?

Accepted Answer

Sweetened tea

Question 7

According to Dalton’s atomic theory, which statement is FALSE?

Accepted Answer

Atoms of one element can change into atoms of another element during a chemical reaction.

Question 8

A pure silver ring contains $$4.22 	imes 10$$^{22}$$ silver atoms. How many moles of silver atoms does it contain? (N_A = 6.022$$ 	imes $$10^{23})$$

Accepted Answer

$$0.0701$$ mol

Question 9

Which of the following best explains why gases are compressible while solids are not?

Accepted Answer

Gas particles are widely spaced and free to move, while solid particles are tightly packed and fixed in place.

Question 10

A titanium cube contains $$8.47 	imes 10$$^{22}$$ titanium atoms. The density of titanium is 4.50$$\ \mathrm{$$g/cm^3$$}$$. What is the edge length of the cube? (Molar mass of Ti = 47.87$$\ \mathrm{g/mol}$$, N_A = 6.022$$ 	imes $$10^{23})$$

Accepted Answer

$$0.362\ \mathrm{cm}$$

Question 11

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

Accepted Answer

Ignoring experimental results that do not fit the hypothesis

Question 12

Which law is illustrated by the fact that 2.67 g of oxygen combines with 1 g of carbon in carbon dioxide, while 1.33 g of oxygen combines with 1 g of carbon in carbon monoxide?

Accepted Answer

Law of multiple proportions

Question 13

How many electrons are in the $$\mathrm{N}^{3-}$$ anion?

Accepted Answer

10

Question 14

Which of the following statements about the nucleus of an atom is correct?

Accepted Answer

It contains most of the atom’s mass and all of its positive charge.

Question 15

Calculate the atomic mass of chlorine if it consists of 75.77% chlorine-35 (mass = 34.97 amu) and 24.23% chlorine-37 (mass = 36.97 amu).

Accepted Answer

$$35.45$$ amu

Question 16

Which of the following is a property of electrical charge?

Accepted Answer

Positive and negative charges of exactly the same magnitude sum to zero when combined.

Question 17

A copper penny has a mass of 3.10 grams. How many copper atoms does it contain? (Molar mass of Cu = $$63.55\ \mathrm{g/mol}$$, $$N_A = 6.022 	imes 10$$^{23}$$)

Accepted Answer

$$2.94 	imes 10$$^{22}$$ atoms

Question 18

Which of the following best describes a scientific theory?

Accepted Answer

A well-established explanation for why a natural phenomenon happens, validated by experimental results.

Question 19

Which of the following is the correct relationship for converting between mass and moles for an element?

Accepted Answer

$$	ext{moles} = \frac{	ext{mass (g)}}{	ext{molar mass (g/mol)}}$$

Atoms: Structure, Properties, and the Foundations of Chemistry

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