Chemical Reactions and Conservation of Mass

How many atoms of hydrogen are in the chemical formula H₂O?

• 1

• 2

• 3

• 4

Tags

NGSS.MS-PS1-1

In the reaction 2Na + Cl₂ → 2NaCl, how many sodium (Na) atoms are there on the reactant side?

• 1

• 2

• 3

• 4

Tags

NGSS.MS-PS1-1

How many chlorine atoms are in the chemical formula NaCl?

• 1

• 2

• 3

• 4

Tags

NGSS.MS-PS1-1

In the reaction C₃H₈ + 5O₂ → 3CO₂ + 4H₂O, how many oxygen (O) atoms are there on the reactant side?

• 2

• 5

• 10

• 15

Tags

NGSS.MS-PS1-5

Identify the number of elements in the chemical equation 2H₂ + O₂ → 2H₂O.

• 1

• 2

• 3

• 4

Tags

NGSS.MS-PS1-1

Which of the following statements is true according to the law of conservation of mass?

• The total mass of reactants is greater than the total mass of products.

• The total mass of reactants is less than the total mass of products.

• The total mass of reactants is equal to the total mass of products.

• The total mass of reactants and products cannot be compared.

Tags

NGSS.MS-PS1-5

Which of the following best describes a balanced chemical equation?

• The number of atoms of each element is the same on both sides of the equation.

• The number of molecules is the same on both sides of the equation.

• The number of compounds is the same on both sides of the equation.

• The number of elements is the same on both sides of the equation.

Tags

NGSS.MS-PS1-5

Which of the following best defines the law of conservation of mass?

• Mass can be created and destroyed.

• Mass is neither created nor destroyed in a chemical reaction.

• Mass is always increasing in a chemical reaction.

• Mass is always decreasing in a chemical reaction.

Tags

NGSS.MS-PS1-5

Identify the number of elements in the chemical equation 2KClO₃ → 2KCl + 3O₂: (a)  

Tags

NGSS.MS-PS1-1

How many oxygen atoms are in the chemical formula CO₂?

• 1

• 2

• 3

• 4

Tags

NGSS.MS-PS1-1