Question 1

Which of the following best describes an element?

Accepted Answer

A substance that cannot be broken down by chemical reactions.

Question 2

What is the atomic number of an element?

Accepted Answer

The number of protons in the nucleus.

Question 3

Which of the following statements about isotopes is correct?

Accepted Answer

Isotopes of an element have the same number of protons and electrons, but different numbers of neutrons.

Question 4

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

$$23 - 11 = 12$$ neutrons

Question 5

Which of the following is a compound?

Accepted Answer

Sodium chloride ($$NaCl)$$

Question 6

Which subatomic particle determines the chemical behavior of an atom?

Accepted Answer

Electron

Question 7

A radioactive isotope has a half-life of 10 years. If you start with 100 grams, how much will remain after 30 years?

Accepted Answer

$$100 \div 2^3$ = 12.5$$ grams

Question 8

Which element is most abundant in the human body by weight?

Accepted Answer

Oxygen

Question 9

Which of the following best explains why water ($$H_2O) is $$considered a compound?

Accepted Answer

It contains two different elements chemically combined in a fixed ratio.

Question 10

If an atom has 8 protons, 8 neutrons, and 8 electrons, what is its atomic mass number?

Accepted Answer

$$8 + 8 = 16$$

Question 11

Which of the following is NOT a biomolecule?

Accepted Answer

Sodium chloride

Question 12

Which subatomic particle has no charge and is found in the nucleus?

Accepted Answer

Neutron

Question 13

A sample contains two isotopes of carbon: $$^{12}C$$ and $$^{14}C. $$What is the difference between these isotopes?

Accepted Answer

They have different numbers of neutrons.

Question 14

Which of the following best describes the relationship between protons and electrons in a neutral atom?

Accepted Answer

The number of protons equals the number of electrons.

Question 15

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

Accepted Answer

Iron

Question 16

Which of the following equations correctly represents the formation of water from hydrogen and oxygen?

Accepted Answer

$$2H_2 + O_2$ \rightarrow 2H_2O$$

Question 17

Which of the following statements about the periodic table is correct?

Accepted Answer

Elements are arranged by increasing atomic number.

Question 18

A patient is given a radioactive isotope for medical imaging. The isotope has a half-life of 6 hours. If the initial dose is 80 mg, how much remains after 18 hours?

Accepted Answer

$$80 \div 2^3$ = 10 mg$$

Question 19

Which of the following best explains why sodium (Na) and chlorine (Cl) form sodium chloride (NaCl)?

Accepted Answer

They react to form a compound with new properties.

Question 20

Which of the following is the correct calculation for the atomic mass number of an atom with 17 protons and 18 neutrons?

Accepted Answer

$$17 + 18 = 35$$

Study Notes: Biomolecules, Elements, and Atomic Structure in Biology

Study Guide - Practice Questions

Study Guide - Flashcards