ATDH - Admission Test for Dental Hygiene Chemical Equations and Reactions Questions and Answers

Question 1

The process of teeth whitening often involves the decomposition of hydrogen peroxide (H₂O₂), which breaks down into water (H₂O) and oxygen gas (O₂).
Which of the following correctly balances the chemical equation for this reaction?

Accepted Answer

2H₂O₂ → 2H₂O + O₂

Answer

H₂O₂ → H₂O + O₂

Answer

H₂O₂ → 2H₂O + O₂

Answer

2H₂O₂ → H₂O + 2O₂

Question 2

A patient's saliva helps to neutralize acidic byproducts from plaque bacteria. The reaction of an acid (like HCl from stomach reflux) with a base (like NaOH) to produce a salt (NaCl) and water (H₂O) is a classic example of what type of chemical reaction?

Accepted Answer

Neutralization

Answer

Decomposition

Answer

Single Replacement

Answer

Combustion

Question 3

The fundamental principle that requires the number of atoms of each element to be identical on both sides of a chemical equation is known as:

Accepted Answer

The Law of Conservation of Mass

Answer

The Law of Definite Proportions

Answer

The Law of Multiple Proportions

Answer

Avogadro's Law

Question 4

In the mouth, salivary amylase is an enzyme that accelerates the breakdown of complex carbohydrates (starch) into simpler sugars. What is the role of salivary amylase in this chemical reaction?

Accepted Answer

A catalyst

Answer

A reactant

Answer

A product

Answer

An inhibitor

Question 5

Phosphoric acid (H₃PO₄) is used in dentistry to etch tooth enamel, while calcium hydroxide (Ca(OH)₂) can be used as a pulp-capping agent. Which of the following are the correct products of the neutralization reaction between these two compounds?

Accepted Answer

Calcium phosphate and dihydrogen monoxide

Answer

Calcium phosphide and hydrogen gas

Answer

Calcium perchlorate and water

Answer

Calcium phosphite and hydrogen peroxide

Question 6

Fluoride ions (F⁻) strengthen tooth enamel by reacting with hydroxyapatite (Ca₁₀(PO₄)₆(OH)₂) to form the more acid-resistant fluorapatite (Ca₁₀(PO₄)₆F₂). Based on the balanced reaction Ca₁₀(PO₄)₆(OH)₂ + 2F⁻ → Ca₁₀(PO₄)₆F₂ + 2OH⁻, what is the stoichiometric mole ratio of hydroxyapatite to fluoride ions?

Accepted Answer

1:2

Answer

10:2

Answer

1:1

Answer

2:1

The process of teeth whitening often involves the decomposition of hydrogen peroxide (H₂O₂), which breaks down into water (H₂O) and oxygen gas (O₂).Which of the following correctly balances the chemical equation for this reaction?

The process of teeth whitening often involves the decomposition of hydrogen peroxide (H₂O₂), which breaks down into water (H₂O) and oxygen gas (O₂).
Which of the following correctly balances the chemical equation for this reaction?