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Which of the following is NOT an indication that a chemical reaction took place?
Question 1 options:

Change in shape

New substance formed

Precipitate forms

Bubbles

Chemical reactions must be because...
Question 2 options:

Larger on the product side because new substances are produced

Not enough information

Smaller on the reactant side because the reactants are used up

Balanced because of the law of conservation of matter and energy

Question 3
Fill in the blank: The number of atoms of an element in a molecule are indicated by the .

Why are buffers important in living organisms?
Question 4 options:

Buffers kill bacteria and viruses

Buffers cause acids to break down food

Buffers make bases work more effectively

Buffers prevent pH changes in body systems

Ionic bonds occur between and .
Question 5 options:

nonmetal and nonmetal

metal and nonmetal

metal and metal