Q: Which of the following statements about the mole is correct?

One mole of any element contains $$6.022 \times 10$$^{23}$$ atoms.

Q: Which of the following best describes the result of Millikan’s oil drop experiment?

The charge of a single electron was determined to be $$1.6 \times 10$$^{-19}$$ C.

Question 1

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

Accepted Answer

A compound always contains the same elements in the same proportion by mass, regardless of the sample source.

Question 2

A sample of carbon dioxide contains 25.6 g of oxygen and 9.60 g of carbon. What is the mass ratio of oxygen to carbon in this sample? (Express your answer as $$\frac{	ext{mass of O}}{	ext{mass of C}})$$

Accepted Answer

$$2.67$$

Question 3

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

Accepted Answer

Rutherford’s gold foil experiment

Question 4

A neutral atom of sodium (Na) has an atomic number of 11. If it loses one electron, what is the resulting charge?

Accepted Answer

$$+1$$

Question 5

Which of the following best explains 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 6

A chlorine isotope has 17 protons and 18 neutrons. What is its isotope symbol using the notation $$^{A}_{Z}X$$?

Accepted Answer

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

Question 7

Which of the following is a homogeneous mixture?

Accepted Answer

Sweetened tea

Question 8

If a sample of ammonia contains 10.0 g of hydrogen and the mass ratio of nitrogen to hydrogen in ammonia is $$0.933:1$$, how many grams of nitrogen does it contain?

Accepted Answer

$$9.33$$

Question 9

Which statement about isotopes is correct?

Accepted Answer

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

Question 10

A sample contains $$3.01 	imes 10$$^{23}$$ atoms of copper. How many moles of copper does it contain? (N_A = 6.022$$ 	imes $$10^{23}$$ mol$$^{-1})$$

Accepted Answer

$$0.500$$ mol

Question 11

Which of the following best describes a compound?

Accepted Answer

A substance composed of two or more elements in fixed, definite proportions.

Question 12

Which of the following is the correct empirical formula for benzene, which has a molecular formula of $$C_6H_6$$?

Accepted Answer

$$CH$$

Question 13

A neutral atom of argon has a mass number of 40 and an atomic number of 18. How many neutrons does it have?

Accepted Answer

$$22$$

Question 14

Which of the following statements about the mole is correct?

Accepted Answer

One mole of any element contains $$6.022 	imes 10$$^{23}$$ atoms.

Question 15

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

Accepted Answer

Gas particles have a lot of space between them, allowing them to be compressed.

Question 16

A sample of water contains $$0.125$$ grams of hydrogen per $$1.00$$ gram of oxygen. A sample of hydrogen peroxide contains $$0.0625$$ grams of hydrogen per $$1.00$$ gram of oxygen. What is the ratio of hydrogen in water to hydrogen in hydrogen peroxide, and does this support the law of multiple proportions?

Accepted Answer

$$2:1$$, supporting the law of multiple proportions

Question 17

Which element has the atomic number 50?

Accepted Answer

Tin

Question 18

A neutral atom of magnesium has 12 protons. How many electrons does it have?

Accepted Answer

12

Question 19

Which of the following best describes the result of Millikan’s oil drop experiment?

Accepted Answer

The charge of a single electron was determined to be $$1.6 	imes 10$$^{-19}$$ C.

Question 20

Which of the following samples contains the most atoms?

Accepted Answer

A 1-g sample of carbon

Atoms: Structure, Properties, and Fundamental Laws in Chemistry

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