$$\text{Mass number} = \text{Number of protons} + \text{Number of neutrons}$$

Question 1

Which of the following statements best explains why iodine is added to table salt in many countries?

Accepted Answer

Iodine is a trace element essential for thyroid function, and its deficiency can cause goiter.

Question 2

A patient is diagnosed with anemia due to iron deficiency. Which of the following best describes the role of iron in the human body?

Accepted Answer

Iron is a component of hemoglobin, which is responsible for oxygen transport in the blood.

Question 3

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

Accepted Answer

An element consists of only one type of atom, while a compound contains two or more elements in a fixed ratio.

Question 4

Which of the following is true regarding isotopes of an element?

Accepted Answer

Isotopes have the same number of protons but different numbers of neutrons.

Question 5

A radioactive isotope is used in PET scans for medical imaging. What property makes radioactive isotopes useful for this purpose?

Accepted Answer

Their nuclei decay spontaneously, emitting detectable particles or energy.

Question 6

Which of the following best describes the arrangement of electrons in a neutral carbon atom?

Accepted Answer

2 electrons in the first shell, 4 electrons in the second shell

Question 7

Which of the following equations correctly represents the calculation of the mass number of an atom?

Accepted Answer

$$	ext{Mass number} = 	ext{Number of protons} + 	ext{Number of neutrons}$$

Question 8

Which of the following best explains why water ($$\mathrm{H_2O}) is $$considered a polar molecule?

Accepted Answer

The electrons are unequally shared between hydrogen and oxygen due to a difference in electronegativity.

Question 9

Which of the following statements about chemical bonds is correct?

Accepted Answer

Ionic bonds form by the transfer of electrons, while covalent bonds form by the sharing of electrons.

Question 10

A solution has a pH of 4. What is the hydrogen ion concentration compared to a solution with a pH of 7?

Accepted Answer

It is $$10^3$$ times higher.

Question 11

Which of the following best describes what happens when an atom loses an electron?

Accepted Answer

It becomes a positively charged ion (cation).

Question 12

Which of the following is a trace element that, when deficient, can lead to weakened immunity against flu and cold?

Accepted Answer

Zinc

Question 13

Which of the following best explains why the mass of an atom is concentrated in its nucleus?

Accepted Answer

Protons and neutrons, which are located in the nucleus, have much greater mass than electrons.

Question 14

Which of the following best describes the effect of adding a base to an acidic solution?

Accepted Answer

The base provides $$\mathrm{OH^-}$$ ions, which decrease the $$\mathrm{H^+}$$ concentration.

Question 15

Which of the following is a correct statement about electronegativity?

Accepted Answer

It is a measure of an atom’s attraction for shared electrons.

Question 16

A scientist is studying a molecule with the formula $$\mathrm{CH_4$}. $$What type of bond is present between the carbon and hydrogen atoms?

Accepted Answer

Non-polar covalent bond

Question 17

Which of the following best describes the relationship between atomic number and the identity of an element?

Accepted Answer

The atomic number is equal to the number of protons, which determines the element.

Question 18

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

Accepted Answer

They are used in PET scans to trace metabolic activity in tissues.

Question 19

If a solution changes from pH 6 to pH 3, by what factor does the hydrogen ion concentration change?

Accepted Answer

$$10^3$$ times increase

Question 20

Which of the following best explains why fluoridation of drinking water is practiced in many communities?

Accepted Answer

Fluoride reduces tooth decay and cavity formation, despite the risk of fluorosis at high levels.

Atoms: Structure, Elements, and Chemical Bonds

Study Guide - Practice Questions