Question 1

Which subatomic particle is responsible for determining the identity of an element?

Accepted Answer

Proton

Question 2

A radioactive isotope of Np-240 has a half-life of 1 hour. If you start with 60 grams, how much will remain after 4 hours?

Accepted Answer

$$\frac{60}{2^4$} = 3.75$$ grams

Question 3

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

Accepted Answer

A molecule consists of two or more atoms bonded together, while a compound consists of two or more elements in a fixed ratio.

Question 4

Which of the following elements is NOT one of the four most essential elements for life?

Accepted Answer

Calcium

Question 5

How many electrons can the first electron shell of an atom hold?

Accepted Answer

2

Question 6

Which type of chemical bond involves the sharing of electron pairs between atoms?

Accepted Answer

Covalent bond

Question 7

What is the main difference between polar and nonpolar covalent bonds?

Accepted Answer

Polar bonds share electrons unequally due to differences in electronegativity, while nonpolar bonds share electrons equally.

Question 8

Which of the following is a property of salts (ionic compounds)?

Accepted Answer

They are typically stable when dry but dissociate easily in water.

Question 9

What is the electron configuration for carbon ($$Z=6$$)?

Accepted Answer

$$1s^2$$\ $$2s^2$$\ $$2p^2$$

Question 10

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

Accepted Answer

Van der Waals interactions

Question 11

If an atom has 17 protons, 18 neutrons, and 17 electrons, what is its atomic number and mass number?

Accepted Answer

Atomic number: 17, Mass number: 35

Question 12

Which statement about chemical reactions is correct?

Accepted Answer

Chemical reactions involve both the making and breaking of chemical bonds.

Question 13

What is the role of neutrons in the atom?

Accepted Answer

They contribute to the atom's mass and can result in isotopes.

Question 14

Which of the following best explains why noble gases are chemically inert?

Accepted Answer

They have a full valence shell of electrons.

Question 15

What is hybridization in the context of molecular bonding?

Accepted Answer

The combination of s and p orbitals to form new, mixed orbitals for bonding.

Question 16

Which of the following is a trace element required by humans?

Accepted Answer

Iron

Question 17

A hydrogen bond forms when:

Accepted Answer

A hydrogen atom is attracted to another electronegative atom, such as oxygen or nitrogen.

Question 18

Which of the following best describes an isotope?

Accepted Answer

Atoms of the same element with different numbers of neutrons.

Question 19

Which equation correctly represents a reversible chemical reaction?

Accepted Answer

$$3H_2 + N_2$ \rightleftharpoons 2NH_3$$

Question 20

Which of the following best explains why water molecules are polar?

Accepted Answer

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

The Chemical Context of Life (Campbell Biology, Chapter 2) - Study Notes

Study Guide - Practice Questions