Question 1

Which statement best describes Dalton's atomic theory as it relates to the composition of compounds?

Accepted Answer

Compounds are composed of atoms of more than one element, and in any compound, the ratio of the numbers of atoms of any two elements present is either an integer or a simple fraction.

Question 2

Which experiment led to the discovery that atoms contain a dense, positively charged nucleus?

Accepted Answer

Rutherford's gold foil experiment

Question 3

An atom of sodium has an atomic number $$Z = 11$$ and a mass number $$A = 23. $$How many neutrons does it contain?

Accepted Answer

$$12$$

Question 4

Which of the following is a correct empirical formula for hydrogen peroxide ($$H_2O_2$$)?

Accepted Answer

$$HO$$

Question 5

A neutral atom of chlorine has $$17$$ protons. How many electrons does a chloride ion ($$Cl^-) $$have?

Accepted Answer

$$18$$

Question 6

Which of the following elements is a halogen?

Accepted Answer

Chlorine

Question 7

Which statement about isotopes is correct?

Accepted Answer

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

Question 8

Which of the following ions has 36 electrons?

Accepted Answer

$$Br^-$$

Question 9

What is the formula for aluminum oxide, given that aluminum forms $$Al^{3+}$$ ions and oxygen forms $$O^{2-}$$ ions?

Accepted Answer

$$Al_2O_3$$

Question 10

Which of the following best explains the law of conservation of mass in a chemical reaction?

Accepted Answer

Atoms are rearranged during a chemical reaction, but the total mass remains unchanged.

Question 11

Which of the following is a diatomic molecule?

Accepted Answer

$$O_2$$

Question 12

A sample contains $$1.5 	imes 10$$^{21}$$ L of seawater, and each mL contains 4.0$$ 	imes $$10^{-6} g of $$gold. What is the total mass of gold in the ocean?

Accepted Answer

$$6.0 	imes 10$$^{15}$$ g

Question 13

Which of the following is a polyatomic ion?

Accepted Answer

$$SO_4$$^{2-}$$

Question 14

Which of the following is the correct formula for magnesium oxide?

Accepted Answer

$$MgO$$

Question 15

Which of the following best describes the difference between a molecule and an ionic compound?

Accepted Answer

A molecule consists of atoms held together by covalent bonds, while an ionic compound consists of cations and anions held together by electrostatic forces.

Question 16

Which of the following is the correct chemical formula for potassium nitrate?

Accepted Answer

$$KNO_3$$

Question 17

Which of the following is an example of an allotrope?

Accepted Answer

Graphite and diamond (forms of carbon)

Question 18

Which of the following ions is formed when calcium loses two electrons?

Accepted Answer

$$Ca^{2+}$$

Question 19

Which of the following is the correct formula for strontium oxide?

Accepted Answer

$$SrO$$

Question 20

Which of the following best describes the charge-to-mass ratio of the electron as determined by Thomson?

Accepted Answer

$$-1.76 	imes 10^8$ C/g

Atoms and the Periodic Table: Atomic Theory, Structure, and Chemical Reactions

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