Chemical Reactions Pretest

Which of these would be evidence that a chemical reaction has occurred?

• Bubbles formed from heating the substance.

• A color change due to red food coloring being added to the reaction.

• An odor is detected that wasn't present before the reaction.

• A temperature change because the reaction was heated.

In this reaction, which substances are the reactants? Check all that apply.

CH₄ + 2O₂ → CO₂ + 2H₂O

• CH₄

• O₂

• CO₂

• H₂O

Which is the name of the kind of solid substance formed in this figure?  

• aqueous 
• precipitate
• acid
• synthesis 

What reaction has the following general formula:

AB --> A + B

• Combination

• Decomposition

• Single Replacement

• Double Replacement

• Combustion

This type of chemical reaction has one reactant that breaks down into two or more products.

• Decomposition

• Synthesis

• Single Replacement

• Double Replacement

• Combustion

what is an ionic compound?

• an example of atoms

  held together by the transferring of electrons

• do not form molecules but instead are called formula units

• the forming of an atom combined with a molecule

• an electron combined with an atom to make a compound

what is the atomic mass?

• 4.0026

• 2

• He

• Helium

How many Hydrogen (H) atoms are there in the chemical formula H₂O?

• 1

• 2

• 3

• 4

What does the subscript tell us in a chemical formula? (For example, the 2 in H₂O)

• Type of element

• Amount of atoms

• Amount of compounds

Na₃PO₄ is the chemical formula of :-

• Sodium hydroxide

• Sodium peroxide

• Sodium phosphate

• Sodium sulfide