Question 1

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

Accepted Answer

A molecule is made of two or more atoms of the same element, while a compound is made of two or more different elements chemically bonded together.

Question 2

Given the periodic table block for carbon, what is the atomic number and what does it represent?

Accepted Answer

The atomic number is 6, which represents the number of protons in the nucleus.

Question 3

How many neutrons are present in the isotope $$^{14}\mathrm{C} ($$Carbon-14)?

Accepted Answer

$$8$$

Question 4

Which of the following elements is NOT one of the four essential elements that make up approximately 96% of living matter?

Accepted Answer

Calcium

Question 5

If an atom has an atomic number of 17 and a mass number of 35, how many neutrons does it have?

Accepted Answer

$$18$$

Question 6

Which statement best describes the behavior of electrons in relation to energy shells?

Accepted Answer

Electrons in higher shells have more potential energy and can only move between shells by absorbing or releasing specific amounts of energy.

Question 7

What is the electron configuration for a neutral neon atom ($$\mathrm{Ne}$$, atomic number 10)?

Accepted Answer

$$1s^2$$\ $$2s^2$$\ $$2p^6$$

Question 8

Which of the following best describes a polar covalent bond?

Accepted Answer

A bond in which electrons are shared unequally between two atoms due to differences in electronegativity.

Question 9

Which of the following is NOT a property of salts (ionic compounds)?

Accepted Answer

They are considered molecules.

Question 10

How many electrons can the second electron shell of an atom hold in total?

Accepted Answer

$$8$$

Question 11

Which of the following best describes a hydrogen bond?

Accepted Answer

A weak attraction between a hydrogen atom covalently bonded to an electronegative atom and another electronegative atom.

Question 12

Which of the following is an example of a van der Waals interaction?

Accepted Answer

Temporary attractions between molecules due to uneven electron distribution, such as a gecko’s toe hairs sticking to a wall.

Question 13

What is the main result of hybridization of atomic orbitals in a molecule like methane ($$\mathrm{CH}_4$$)?

Accepted Answer

The formation of four equivalent hybrid orbitals arranged in a tetrahedral shape.

Question 14

A radioactive isotope has a half-life of 2 hours. If you start with 80 grams, how much will remain after 6 hours?

Accepted Answer

$$10$$ grams

Question 15

Which of the following best describes chemical equilibrium?

Accepted Answer

The forward and reverse reactions occur at the same rate, and the concentrations of reactants and products remain constant.

Question 16

Which of the following is true about isotopes?

Accepted Answer

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

Question 17

Which of the following best explains why noble gases are chemically inert?

Accepted Answer

They have a full valence shell of electrons.

Question 18

Which of the following is the correct electron configuration for carbon ($$\mathrm{C}$$, atomic number 6)?

Accepted Answer

$$1s^2$$\ $$2s^2$$\ $$2p^2$$

Question 19

Which of the following best describes the process shown in the reaction: $$2\ \mathrm{H}_2 + \mathrm{O}_2 \rightarrow 2\ \mathrm{H}_2\mathrm{O}$$?

Accepted Answer

A chemical reaction where hydrogen and oxygen react to form water.

Question 20

Which of the following is a trace element required by living organisms?

Accepted Answer

Iron

Atoms, Elements, and Chemical Bonding: Study Notes for GOB Chemistry

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