TEAS Most common Chemistry Questions 2026

What is the chemical formula for water?

A) CO2

B) H2O

C) H2O2

D) O2

B) H2O

Which of the following is an example of an exothermic reaction?

A) Melting ice cubes

B) Burning wood

C) Boiling water

D) Photosynthesis

B) Burning wood

A student dissolves NaOH in water and the temperature of the solution rises. What can be concluded?

A) The dissolution is exothermic

B) The dissolution is endothermic

C) The solution becomes less basic

D) The NaOH forms covalent bonds with water

A) The dissolution is exothermic

Which of the following is the atomic number of an atom that has 12 protons and 12 neutrons?

A.) 24

B.) 0

C.) 12

D.) 6

C.) 12

Which of the following explains why noble gases are generally unreactive?

A.) They have low atomic mass

B.) They are nonpolar molecules

C.) Their outer electrons shells are full

D.) They are always found in ionic compounds

C.) Their outer electrons shells are full

Nitrogen gas is an extremely stable molecule because of which of the following?

A.) It has a full outer shell of 6 electrons

B.) It forms a single bond with another nitrogen atom

C.) it has low electronegativity

D.) It forms triple covalent bonds

D.) It forms triple covalent bonds

Which of the following substance contains the greatest number of atoms?

A.) 1 mole of H2

B.) 1 mole of NaCl

C.) 1 mole of H2O

D.) 1 mole of O3

C.) 1 mole of H2O

Which of the following summarizes a change that takes place as a solid turns into a liquid?

A.) Particles become less ordered

B.) Particles completely stop moving

C.) Temperature decreases drastically

D.) Particles gain protons and neutrons

A.) Particles become less ordered

Which of the following describes the role of a catalyst in a chemical reaction?

A.) Increases the activation energy

B.) Decreases the energy of the products

C.) Increases the temperature of the system

D.) Gives an alternative reaction pathway with lower activation enegy

D.) Gives an alternative reaction pathway with lower activation enegy

Which of the following occurs in an oxidation reactions?

A.) Gain of protons

B.) Removal of electrons

C.) Decrease in oxidation state

D.) Absorption of neutrons

B.) Removal of electrons

Which of the following is a physical change, not a chemical change?

A.) Iron rusting

B.) Wood burning

C.) Water Boiling

D.) Vinegar reacting with baking soda

C.) Water Boiling

Which of the following atoms is most likely to become an anion?

A.) Fluorine - Atomic #9

B.) Sodium - Atomic # 11

C.) Magnesium - Atomic # 12

D.) Neon - Atomic # 10

A.) Fluorine - Atomic #9

What happens to the pH when a strong acid is added to a solution?

A.) pH increases

B.) pH becomes 14

C.) pH remains constant

D.) pH decrease

D.) pH decrease

Freshly cut avocados tend to turn brown when exposed to air, but squeezing lime juice over the surface helps them stay green. Which of the following best explains this effect?

Freshly cut avocados tend to turn brown when exposed to air, but squeezing lime juice over the surface helps them stay green. Which of the following best explains this effect?

A.) Lime juice raises the temperature and speeds up oxidation

B.) Lime juice has a pH that inactivates the enzymes responsible for brownig

C.) The water in the limes juice dilutes the color change

D.) The lime juice reacts with oxygen to produce energy

B.) Lime juice has a pH that inactivates the enzymes responsible for browning

Using the formula pH= -log [H+], a solution with hydrogen ion concentration of [H+] = 10-1M has a pH of which of the following?

A.) 0

B.) 10

C.) 1

D.) -1

C.) 1