Question 1

Which of the following best describes a compound?

Accepted Answer

A substance consisting of two or more different elements combined in a fixed ratio.

Question 2

Which of the following are compounds? Select the correct answer.

Accepted Answer

H$$_2O $$and CH$$_4$$

Question 3

Which three elements are the most abundant in the human body?

Accepted Answer

Oxygen, Carbon, Hydrogen

Question 4

Which of the following is a trace element commonly added to food or water to prevent disease?

Accepted Answer

Iron

Question 5

What is the smallest unit of matter that still retains the properties of an element?

Accepted Answer

Atom

Question 6

Which subatomic particles are located in the nucleus of an atom?

Accepted Answer

Protons and neutrons

Question 7

The atomic number of an element is defined as:

Accepted Answer

The number of protons in the nucleus

Question 8

An isotope is best described as:

Accepted Answer

An atom with a different number of neutrons

Question 9

A radioactive isotope is one that:

Accepted Answer

Decays spontaneously, releasing energy

Question 10

Which shell determines the chemical properties of an atom?

Accepted Answer

The outermost shell (valence shell)

Question 11

What type of chemical bond involves the sharing of electrons between atoms?

Accepted Answer

Covalent bond

Question 12

Which of the following best describes an ionic bond?

Accepted Answer

A bond formed by transferring electrons from one atom to another

Question 13

When sodium (Na) donates an electron to chlorine (Cl) to form NaCl, what happens to the charges of the resulting ions?

Accepted Answer

Sodium becomes positively charged, chlorine becomes negatively charged

Question 14

Which of the following is a weak bond that plays a crucial role in the structure of DNA and proteins?

Accepted Answer

Hydrogen bond

Question 15

A hydrogen bond forms when:

Accepted Answer

A hydrogen atom with a slightly positive charge is attracted to an atom with a slightly negative charge

Question 16

In a chemical reaction, the starting materials are called:

Accepted Answer

Reactants

Question 17

Which statement best explains the law of conservation of matter as it applies to chemical reactions?

Accepted Answer

Chemical reactions only rearrange matter; they do not create or destroy it.

Question 18

Which of the following scenarios best illustrates the difference between a molecule and a compound?

Accepted Answer

O$$_2 is a $$molecule but not a compound, while H$$_2O is $$both a molecule and a compound.

Question 19

Which of the following best describes a valence shell?

Accepted Answer

The outermost electron shell that determines chemical properties

Question 20

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

Accepted Answer

Atomic number = 6, Mass number = 12

Chapter 2: Elements, Atoms, and Chemical Bonds – Guided Study

Study Guide - Practice Questions