Question 1

Which of the following statements best describes a compound?

Accepted Answer

A compound is 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

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

Accepted Answer

$$12$$

Question 5

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

Accepted Answer

They have the same number of electrons and protons.

Question 6

Which type of chemical bond involves the sharing of a pair of valence electrons between two atoms?

Accepted Answer

Covalent bond

Question 7

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

Accepted Answer

Polar covalent bonds involve unequal sharing of electrons, while nonpolar covalent bonds involve equal sharing.

Question 8

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

Accepted Answer

Dating fossils

Question 9

What is the maximum number of electrons that can occupy the innermost electron shell of an atom?

Accepted Answer

$$2$$

Question 10

Which property of an atom determines its chemical reactivity?

Accepted Answer

The number of electrons in its outermost (valence) shell

Question 11

What is the result when an atom loses an electron?

Accepted Answer

It becomes a positively charged ion (cation)

Question 12

Which of the following best describes a hydrogen bond?

Accepted Answer

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

Question 13

Which interaction is responsible for the ability of geckos to climb smooth surfaces?

Accepted Answer

Van der Waals interactions

Question 14

During photosynthesis, which molecules are the reactants and which are the products?

Accepted Answer

Reactants: $$6CO_2$$ and $$6H_2O$$; Products: $$C_6H_{12}O_6$ and 6O_2$

Question 15

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

Accepted Answer

Iron (Fe)

Question 16

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

Accepted Answer

They have full valence electron shells.

Question 17

Which of the following best describes electronegativity?

Accepted Answer

An atom's attraction for the electrons in a covalent bond

Question 18

Which of the following is true about weak chemical bonds?

Accepted Answer

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

Question 19

A molecule of methane ($$CH_4) $$contains how many single covalent bonds?

Accepted Answer

$$4$$

Question 20

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

Accepted Answer

A molecule is two or more atoms held together by covalent bonds, while a compound is a molecule that contains two or more different elements.

Chapter 2: Chemical Context of Life – Study Notes

Study Guide - Practice Questions