Chemical Changes and Chemical Formulas

This appears on the left side of a chemical formula, and represents how many molecules there are.

• an atom
• the subscript
• a molecule
• the coefficient

How many hydrogen atoms are in this chemical formula?

• 4 hydrogen atoms
• 1 hydrogen atom
• 2 hydrogen atoms
• 3 hydrogen atoms

Tags

NGSS.MS-PS1-1

How many oxygen atoms are in this chemical formula?

• 7 oxygen atoms
• 4 oxygen atoms
• 3 oxygen atoms
• 1 oxygen atom

How many oxygen atoms are in this chemical formula?

• 6 oxygen atoms
• 2 oxygen atoms
• 3 oxygen atoms
• 4 oxygen atoms

Tags

NGSS.MS-PS1-1

Is this balanced?
2HgO  →  2Hg  +  O₂

• Yes
• No

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

Is this balanced?
Al + O2 → 2Al₂O₃

• Yes
• No

Tags

NGSS.MS-PS1-5

Law of conservation of matter states that ____.

• Matter can be created
• Matter can be destroyed
• Matter can neither be created nor destroyed
• Matter does not change

Tags

NGSS.MS-PS1-5

The law of conservation of matter means that the number of atoms in a chemical reaction have to be the same for the reactants and products.

• True
• False

Tags

NGSS.MS-PS1-5

The total amount of matter (atoms) before and after a chemical reaction (change), remains the same.

• True
• False

Tags

NGSS.MS-PS1-5

What will weigh more when a chemical change is complete? The reactants before the chemical reaction, or the product after the reaction is complete?

• They both will weigh the same.
• The product always weighs more than the reactant.
• The reactant will weigh more than the product.
• They both will lose mass after the reaction.

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5