Q: Which of the following is the correct formula for calculating the atomic mass of an atom?

$$\text{Atomic mass} = \text{Number of protons} + \text{Number of neutrons}$$

Question 1

Which of the following best explains why atoms are considered the fundamental building blocks of matter in living organisms?

Accepted Answer

Atoms combine to form molecules, which make up the structures and functions of cells.

Question 2

If the nucleus of an atom were the size of a baseball, about how far away would the electron cloud extend, according to the analogy provided in the study materials?

Accepted Answer

About 5 football fields away.

Question 3

Which force is responsible for holding protons and neutrons together in the nucleus of an atom?

Accepted Answer

Strong nuclear force

Question 4

Why don't electrons simply fall into the nucleus, despite the attraction between opposite charges?

Accepted Answer

Electrons have too much energy to be confined in the nucleus.

Question 5

Which of the following statements about isotopes is correct?

Accepted Answer

Isotopes of an element have different numbers of neutrons.

Question 6

A radioactive isotope of carbon, carbon-14, is used in radiometric dating. If the half-life of carbon-14 is 5,730 years, how much of a 100-gram sample would remain after 11,460 years?

Accepted Answer

$$12.5$$ grams

Question 7

Which element makes up the largest percentage of the human body by mass?

Accepted Answer

Oxygen

Question 8

What is the atomic number of an element, and what does it represent?

Accepted Answer

The number of protons in the nucleus

Question 9

Which of the following best describes why you cannot walk through walls, even though atoms are mostly empty space?

Accepted Answer

The electron clouds of atoms repel each other due to electromagnetic forces.

Question 10

Which of the following is a correct statement about electron shells in atoms?

Accepted Answer

The first shell can hold up to 2 electrons, and the second shell up to 8 electrons.

Question 11

A patient is injected with a radioactive tracer for a medical scan. Which property of isotopes makes this possible?

Accepted Answer

Radioactive isotopes emit detectable energy as they decay.

Question 12

Which of the following best explains the origin of the elements found in living organisms?

Accepted Answer

Elements were formed in stars and distributed by supernovae.

Question 13

Which of the following is the correct formula for calculating the atomic mass of an atom?

Accepted Answer

$$	ext{Atomic mass} = 	ext{Number of protons} + 	ext{Number of neutrons}$$

Question 14

Which of the following elements is NOT one of the four most abundant elements in the human body?

Accepted Answer

Calcium

Question 15

A neutral atom of sodium (Na) has an atomic number of 11 and an atomic mass of 23. How many neutrons does it have?

Accepted Answer

$$12$$

Question 16

Which of the following best describes the arrangement of electrons in an atom's electron shells?

Accepted Answer

Electrons fill the innermost shell first, then move to outer shells as needed.

Question 17

Which of the following is a trace element in the human body, required in very small amounts?

Accepted Answer

Iron

Question 18

Which of the following best explains why isotopes of the same element have nearly identical chemical properties?

Accepted Answer

They have the same number of protons and electrons.

Question 19

Which of the following is the correct order of biological organization from smallest to largest?

Accepted Answer

Atom, molecule, cell, tissue, organ

Question 20

If a stable isotope of carbon has 6 protons and 7 neutrons, what is its atomic mass?

Accepted Answer

$$13$$

Atoms, Elements, and the Chemical Basis of Life

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