Question 1

Which statement best describes the difference between an atom and an element?

Accepted Answer

An atom is the smallest identifiable unit of an element, and an element is a substance that cannot be broken down into simpler substances.

Question 2

Which experiment led to the discovery that atoms have a small, dense nucleus?

Accepted Answer

Rutherford’s gold foil experiment

Question 3

According to Dalton’s atomic theory, which of the following is NOT true?

Accepted Answer

Atoms can be divided into smaller, indestructible particles.

Question 4

Which of the following best explains why metals are good conductors of electricity?

Accepted Answer

Metals have free-moving electrons that allow for the flow of electrical charge.

Question 5

A neutral atom of sodium (Na) has 11 protons. How many electrons does it have?

Accepted Answer

11

Question 6

Which of the following elements is a metalloid and is widely used in the electronics industry due to its semiconductor properties?

Accepted Answer

Silicon (Si)

Question 7

What is the charge of an ion with 17 protons and 18 electrons?

Accepted Answer

$$-1$$

Question 8

Which group in the periodic table contains elements that are chemically inert and do not readily form compounds?

Accepted Answer

Noble gases

Question 9

A chlorine atom has 17 protons and 18 neutrons. What is its mass number?

Accepted Answer

$$35$$

Question 10

Which of the following best describes an isotope?

Accepted Answer

Atoms of the same element with different numbers of neutrons.

Question 11

Calculate the average atomic mass of an element that has two isotopes: 60% with mass $$10$$ amu and 40% with mass $$12$$ amu.

Accepted Answer

$$11.2$$ amu

Question 12

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

Accepted Answer

Elements in the same group have similar chemical properties.

Question 13

Which scientist is credited with organizing the periodic table based on recurring properties?

Accepted Answer

Dmitri Mendeleev

Question 14

What is the formula to determine the charge of an ion?

Accepted Answer

$$\mathrm{ion\ charge} = \mathrm{number\ of\ protons} - \mathrm{number\ of\ electrons}$$

Question 15

Which of the following is a property of nonmetals?

Accepted Answer

They tend to gain electrons in chemical reactions.

Question 16

A gallium sample contains 60.11% Ga-69 (mass $$68.9256$$ amu) and 39.89% Ga-71 (mass $$70.9247$$ amu). What is the atomic mass of gallium?

Accepted Answer

$$69.72$$ amu

Question 17

Which of the following best describes the difference between a cation and an anion?

Accepted Answer

A cation is formed when an atom loses electrons, while an anion is formed when an atom gains electrons.

Question 18

Which of the following is a real-world application of radioactive isotopes?

Accepted Answer

They are used in diagnosing diseases through medical imaging.

Question 19

If an atom has an atomic number $$Z = 8$$ and a mass number $$A = 16$$, how many neutrons does it have?

Accepted Answer

$$8$$

Question 20

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

Accepted Answer

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

Atoms and Elements: Foundations of Matter

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