$$6CO_2 + 6H_2O + \text{Energy (solar)} \rightarrow C_6H_{12}O_6$ + 6O_2$$

Question 1

Which of the following best describes a chemical element?

Accepted Answer

A substance that cannot be broken down into other substances by chemical reactions

Question 2

What is the atomic number of an element?

Accepted Answer

The number of protons found in the nucleus of an atom

Question 3

Which of the following statements about isotopes is correct?

Accepted Answer

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

Question 4

Which subatomic particle is responsible for the chemical behavior of an atom?

Accepted Answer

Electron

Question 5

A sodium atom (Na) has 11 protons and 12 neutrons. What is its atomic mass?

Accepted Answer

$$23$$

Question 6

Which type of chemical bond is formed by the sharing of valence electrons between atoms?

Accepted Answer

Covalent bond

Question 7

What causes the formation of an ionic bond?

Accepted Answer

Transfer of electrons between atoms with a large difference in electronegativity

Question 8

Which of the following is a trace element essential for human life?

Accepted Answer

Iron (Fe)

Question 9

Which of the following best explains why water molecules are attracted to each other?

Accepted Answer

Hydrogen bonds between the slightly positive hydrogen and slightly negative oxygen atoms

Question 10

Which equation correctly represents the process of photosynthesis?

Accepted Answer

$$6CO_2 + 6H_2O + 	ext{Energy (solar)} ightarrow C_6H_{12}O_6$ + 6O_2$$

Question 11

Which of the following statements about chemical equilibrium is correct?

Accepted Answer

At equilibrium, the forward and reverse reactions occur at equal rates

Question 12

Which of the following best describes a molecule?

Accepted Answer

A substance composed of two or more atoms connected by chemical bonds

Question 13

Which of the following is true about van der Waals interactions?

Accepted Answer

They are weak attractions due to random non-symmetrical distribution of electrons

Question 14

If an atom has 8 protons, 8 neutrons, and 8 electrons, what is its atomic number and atomic mass?

Accepted Answer

Atomic number: $$8$$, Atomic mass: $$16$$

Question 15

Which of the following is a property of a cation?

Accepted Answer

It has lost electrons and has a positive charge

Question 16

Which of the following best explains why sodium chloride (NaCl) forms from sodium and chlorine?

Accepted Answer

Sodium transfers an electron to chlorine, forming an ionic bond

Question 17

Which of the following is true about the energy levels of electrons in an atom?

Accepted Answer

Electrons farther from the nucleus have higher potential energy

Question 18

Which of the following is a real-world example of a reversible chemical reaction?

Accepted Answer

The conversion between glucose and carbon dioxide in living cells

Question 19

Which of the following best describes a polar covalent bond?

Accepted Answer

A bond where electrons are shared unequally due to differences in electronegativity

Question 20

Which of the following is the correct formula for the atomic mass of an atom?

Accepted Answer

$$	ext{Atomic mass} = 	ext{Number of protons} + 	ext{Number of neutrons}$$

The Chemical Context of Life: Atoms, Elements, and Chemical Bonds

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