Question 1

Which of the following statements best describes Dalton’s postulate regarding the identity of atoms in a chemical reaction?

Accepted Answer

Atoms are neither created nor destroyed in chemical reactions; they are simply rearranged.

Question 2

J.J. Thomson’s cathode ray tube experiment led to the discovery of which subatomic particle, and what property did he measure?

Accepted Answer

Electron; charge-to-mass ratio

Question 3

Which experiment provided evidence for the existence of the atomic nucleus?

Accepted Answer

Rutherford’s gold foil experiment

Question 4

A neutral atom of chromium-52 ($$^{52}_{24}\mathrm{Cr}) $$contains how many protons, neutrons, and electrons?

Accepted Answer

24 protons, 28 neutrons, 24 electrons

Question 5

Which of the following best explains why sodium metal (Na) is highly reactive, but sodium ions ($$\mathrm{Na}^+) in $$table salt are stable?

Accepted Answer

Sodium ions have a complete outer electron shell, making them stable.

Question 6

Calculate the average atomic mass of gallium given the following data: $$^{69}\mathrm{Ga} (60.11$$%, 68.9256 amu) and $$^{71}\mathrm{Ga} (39.89$$%, 70.9247 amu).

Accepted Answer

$$69.72$$ amu

Question 7

Which of the following ions is correctly matched with its charge?

Accepted Answer

Sulfide anion: $$\mathrm{S}^{2-}$$

Question 8

Which property is NOT characteristic of metals?

Accepted Answer

Forms anions in reactions

Question 9

A fluorine atom ($$^{19}\mathrm{F}) $$gains one electron to become a fluoride ion. What is the resulting number of protons, neutrons, and electrons?

Accepted Answer

9 protons, 10 neutrons, 10 electrons

Question 10

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 11

Which element is a metalloid and what property does it exhibit?

Accepted Answer

Silicon; conducts electricity but not heat well

Question 12

Which of the following best describes the difference between the plum pudding model and the nuclear model of the atom?

Accepted Answer

The nuclear model has a dense, positively charged nucleus with electrons in empty space, while the plum pudding model has electrons embedded in a positive sphere.

Question 13

Which of the following is the correct symbol for an aluminum ion with a $$+3$$ charge?

Accepted Answer

$$\mathrm{Al}^{3+}$$

Question 14

Which of the following best explains why the mass of an atom is concentrated in its nucleus?

Accepted Answer

The nucleus contains protons and neutrons, which are much more massive than electrons.

Question 15

Which of the following elements is most likely to form a $$2+$$ cation based on its position in the periodic table?

Accepted Answer

Strontium

Question 16

A sample of copper contains 69.17% $$^{63}\mathrm{Cu} (62.9396 $$amu) and 30.83% $$^{65}\mathrm{Cu} (64.9278 $$amu). What is the average atomic mass of copper?

Accepted Answer

$$63.55$$ amu

Question 17

Which of the following best describes the charge and mass of a neutron?

Accepted Answer

No charge, mass approximately 1 amu

Question 18

Which of the following is a correct statement about the periodic table?

Accepted Answer

Elements in the same group have similar chemical properties.

Question 19

Which of the following best describes the behavior of nonmetals in chemical reactions?

Accepted Answer

They tend to gain electrons and form anions.

Question 20

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

Accepted Answer

$$\mathrm{O}^{2-}$$

Atoms, Elements, and the Structure of Matter: Foundations of Atomic Theory

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