Question 1

Which of the following statements best describes an isotope?

Accepted Answer

An isotope is an atom with a different number of neutrons than other atoms of the same element.

Question 2

Which subatomic particle determines the atomic number of an element?

Accepted Answer

Proton

Question 3

If an atom has 6 protons, 6 neutrons, and 6 electrons, what is its mass number?

Accepted Answer

$$12$$

Question 4

Which of the following best explains why oxygen is more electronegative than hydrogen?

Accepted Answer

Oxygen has more protons, which increases its ability to attract electrons.

Question 5

Which of the following is true about covalent bonds?

Accepted Answer

Covalent bonds involve the sharing of a pair of valence electrons between two atoms.

Question 6

A molecule of water ($$\mathrm{H_2O}) is $$held together by which type of bond between its atoms?

Accepted Answer

Covalent bond

Question 7

Which of the following best describes a hydrogen bond?

Accepted Answer

A hydrogen bond is a weak attraction between a partially positive hydrogen atom and a partially negative atom in another molecule.

Question 8

Which of the following statements about ionic bonds is correct?

Accepted Answer

Ionic bonds form when one atom transfers electrons to another atom, resulting in oppositely charged ions that attract each other.

Question 9

Which of the following best explains why sodium chloride ($$\mathrm{NaCl}) $$dissolves easily in water?

Accepted Answer

Water molecules are polar and can surround the positive sodium ions and negative chloride ions, separating them.

Question 10

Which of the following is an example of a chemical reaction?

Accepted Answer

Combining hydrogen and oxygen to form water: $$2\mathrm{H_2$} + \mathrm{O_2$} \rightarrow 2\mathrm{H_2O}$$

Question 11

Which of the following best describes the role of valence electrons in chemical bonding?

Accepted Answer

Valence electrons are shared or transferred between atoms to form chemical bonds.

Question 12

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

Accepted Answer

Calcium

Question 13

What is the main difference between a polar covalent bond and a nonpolar covalent bond?

Accepted Answer

Polar covalent bonds have unequal sharing of electrons due to differences in electronegativity, while nonpolar covalent bonds have equal sharing.

Question 14

Which of the following best describes the concept of chemical equilibrium?

Accepted Answer

Chemical equilibrium is reached when the forward and reverse reactions occur at the same rate.

Question 15

Which of the following particles has a negative charge and is found outside the nucleus?

Accepted Answer

Electron

Question 16

A molecule's shape is primarily determined by:

Accepted Answer

The arrangement of its atoms and the types of bonds between them

Question 17

Which of the following is a trace element required by living organisms in only minute quantities?

Accepted Answer

Iron

Question 18

Which of the following best explains why weak chemical bonds, such as hydrogen bonds, are important in biological systems?

Accepted Answer

They enable reversible interactions that are essential for processes like DNA replication and enzyme function.

Question 19

Which of the following best describes a cation?

Accepted Answer

A cation is a positively charged ion formed by losing electrons.

Atoms, Elements, Chemical Bonds, and Chemical Reactions: General Biology Study Notes

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