Q: Which of the following is the correct calculation for the average atomic mass of chlorine, given 75.77% $$^{35}\mathrm{Cl} ($$mass 34.97 amu) and 24.23% $$^{37}\mathrm{Cl} ($$mass 36.97 amu)?

$$0.7577 \times 34.97 + 0.2423 \times 36.97$$

Question 1

Which of the following statements best describes the main contribution of John Dalton to atomic theory?

Accepted Answer

He proposed that all matter is composed of indivisible particles called atoms, and that atoms of each element are identical.

Question 2

A sample of methane reacts with oxygen to produce carbon dioxide and water. If 16.0 g of methane reacts with 64.0 g of oxygen and produces 36.0 g of water, how many grams of carbon dioxide are produced? Use the law of conservation of mass.

Accepted Answer

$$44.0\ \mathrm{g}$$

Question 3

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

Accepted Answer

Gold foil experiment

Question 4

Which of the following best explains why most alpha particles passed straight through the gold foil in Rutherford’s experiment?

Accepted Answer

Most of the atom is empty space.

Question 5

Which of the following is the correct isotope symbol for an atom with 19 protons, 19 electrons, and 20 neutrons?

Accepted Answer

$$^{39}_{19}\mathrm{K}$$

Question 6

A neutral atom of magnesium has an atomic number of 12 and a mass number of 24. How many protons, neutrons, and electrons does it have?

Accepted Answer

12 protons, 12 neutrons, 12 electrons

Question 7

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 8

Which property is NOT characteristic of metals?

Accepted Answer

Brittle

Question 9

Which group on the periodic table contains elements that are generally unreactive and exist as gases at room temperature?

Accepted Answer

Group 8A (Noble gases)

Question 10

A fluorine atom gains one electron to form an ion. What is the charge on the resulting ion, and how many electrons does it have?

Accepted Answer

Charge: $$-1$$, 10 electrons

Question 11

Which of the following best describes the law of multiple proportions as predicted by Dalton’s atomic theory?

Accepted Answer

When two elements form more than one compound, the masses of one element that combine with a fixed mass of the other are in small, whole-number ratios.

Question 12

Which of the following is a metalloid and what property does it share with both metals and nonmetals?

Accepted Answer

Silicon; it is a good conductor of heat and is brittle.

Question 13

Which of the following best explains why lightning occurs during an electrical storm?

Accepted Answer

The charge balance of matter is disturbed, leading to a dramatic rebalancing of positive and negative charges.

Question 14

Which of the following is the correct calculation for the average atomic mass of chlorine, given 75.77% $$^{35}\mathrm{Cl} ($$mass 34.97 amu) and 24.23% $$^{37}\mathrm{Cl} ($$mass 36.97 amu)?

Accepted Answer

$$0.7577 	imes 34.97 + 0.2423 	imes 36.97$$

Question 15

Which of the following statements about the periodic table is correct?

Accepted Answer

Elements are arranged in order of increasing atomic number.

Question 16

Which of the following ions is formed when a magnesium atom loses two electrons?

Accepted Answer

$$\mathrm{Mg}^{2+}$$

Question 17

Which property distinguishes nonmetals from metals?

Accepted Answer

Nonmetals are generally brittle and dull.

Question 18

Which scientist is credited with the first meaningful atomic theory that explained the law of conservation of mass and the law of multiple proportions?

Accepted Answer

John Dalton

Question 19

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

Accepted Answer

Charge: $$0$$, Mass: $$1.0087$$ amu

Atomic Theory and Structure: Foundations of Modern Chemistry

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