$$\text{Number of neutrons} = \text{Atomic mass} - \text{Atomic number}$$

Question 1

Which of the following statements best describes an element in the context of biology?

Accepted Answer

An element is a substance that cannot be broken down to other substances by chemical reactions.

Question 2

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

Accepted Answer

Carbon, hydrogen, oxygen, and nitrogen

Question 3

If an atom has an atomic number of 8 and a mass number of 16, how many neutrons does it have?

Accepted Answer

$$16 - 8 = 8$$ neutrons

Question 4

Which of the following is NOT considered an essential element for life?

Accepted Answer

Lead

Question 5

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

Accepted Answer

11 electrons

Question 6

Which element is present in the highest percentage in the human body by mass?

Accepted Answer

Oxygen

Question 7

What is the main reason noble gases are chemically nonreactive?

Accepted Answer

They have a full valence electron shell.

Question 8

Which of the following best explains why radioactive isotopes are useful in medical imaging (such as PET scans)?

Accepted Answer

They give off particles and energy that can be traced in the body.

Question 9

Which of the following equations correctly calculates the number of neutrons in an atom?

Accepted Answer

$$	ext{Number of neutrons} = 	ext{Atomic mass} - 	ext{Atomic number}$$

Question 10

Which of the following elements is considered a trace element in the human body?

Accepted Answer

Iron

Question 11

An atom of phosphorus has an atomic number of 15 and a mass number of 31. How many neutrons does it have?

Accepted Answer

$$31 - 15 = 16$$ neutrons

Question 12

Which of the following best describes the role of valence electrons in chemical bonding?

Accepted Answer

Valence electrons determine the number and kinds of chemical bonds an atom can form.

Question 13

A fluorine atom has an atomic number of 9 and a mass number of 19. How many neutrons does it have?

Accepted Answer

$$19 - 9 = 10$$ neutrons

Question 14

Which of the following elements is most likely to form the same number of covalent bonds as nitrogen?

Accepted Answer

Phosphorus

Question 15

Which statement about atoms is correct?

Accepted Answer

Atoms are neutral when the number of protons equals the number of electrons.

Question 16

Which of the following best describes potential energy in the context of electrons in an atom?

Accepted Answer

Potential energy is the energy electrons have due to their distance from the atomic nucleus.

Question 17

Which element is present in the human body at approximately 1.5% by mass?

Accepted Answer

Calcium

Question 18

If an atom gains an electron, what type of ion does it become?

Accepted Answer

A negative ion (anion)

Question 19

Which of the following is a correct statement about trace elements?

Accepted Answer

Trace elements are required by organisms in only minute quantities.

Question 20

Which of the following elements is NOT a major component of the human body?

Accepted Answer

Sodium

The Chemical Context of Life: Atomic Structure and Elements in Biology

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