$$\text{Mass Number} = \text{Number of Protons} + \text{Number of Neutrons}$$

Question 1

Which of the following statements best describes a compound?

Accepted Answer

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

Question 2

Which four elements make up approximately 96% of living matter?

Accepted Answer

Carbon, hydrogen, oxygen, and nitrogen

Question 3

What is the atomic number of an element?

Accepted Answer

The number of protons in the nucleus

Question 4

Which of the following best explains why isotopes of an element behave similarly in chemical reactions?

Accepted Answer

They have the same number of protons and electrons.

Question 5

A radioactive isotope is useful in medical imaging because:

Accepted Answer

It emits energy that can be detected as it decays.

Question 6

Which of the following best describes a covalent bond?

Accepted Answer

A sharing of a pair of valence electrons by two atoms

Question 7

What is the main reason noble gases such as helium and neon are chemically inert?

Accepted Answer

Their outermost electron shell is full.

Question 8

Which of the following is true about polar covalent bonds?

Accepted Answer

Electrons are shared unequally, resulting in partial charges.

Question 9

What is the correct formula for calculating the mass number of an atom?

Accepted Answer

$$	ext{Mass Number} = 	ext{Number of Protons} + 	ext{Number of Neutrons}$$

Question 10

Which type of chemical bond is primarily responsible for the unique properties of water, such as its high boiling point and surface tension?

Accepted Answer

Hydrogen bonds

Question 11

A sodium atom transfers an electron to a chlorine atom, forming NaCl. What type of bond holds Na+ and Cl- together?

Accepted Answer

Ionic bond

Question 12

Which of the following best describes van der Waals interactions?

Accepted Answer

Weak attractions due to temporary 'hot spots' of charge

Question 13

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

Accepted Answer

Iron

Question 14

Which statement about chemical reactions is correct?

Accepted Answer

Chemical reactions involve the making and breaking of chemical bonds.

Question 15

Which of the following best explains why water is a polar molecule?

Accepted Answer

Oxygen is more electronegative than hydrogen, causing unequal sharing of electrons.

Question 16

If an atom has an atomic number of 7 and a mass number of 15, how many neutrons does it have?

Accepted Answer

8

Question 17

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

Accepted Answer

Dating ancient fossils using carbon-14

Question 18

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

Accepted Answer

A compound consists of two or more different elements, while a molecule can consist of the same or different elements.

Question 19

Which of the following statements about energy levels of electrons is correct?

Accepted Answer

Electrons in the outermost shell have more energy than those closer to the nucleus.

Question 20

Which of the following best describes the role of weak chemical bonds in biological molecules?

Accepted Answer

They reinforce the shapes of large molecules and help molecules adhere to each other.

Chapter 2: The Chemical Context of Life – Study Notes

Study Guide - Practice Questions