RPAL Conservation of Mass

Question 1

Which law states that matter is neither created nor destroyed in a chemical reaction?

Accepted Answer

Law of Conservation of Mass

Answer

Law of Definite Proportions

Answer

Law of Multiple Proportions

Answer

Law of Conservation of Energy

Question 2

In a sealed container, 10 g of reactant A reacts completely with 5 g of reactant B. What is the total mass of products formed?

Accepted Answer

15 g

Answer

5 g

Answer

10 g

Answer

20 g

Question 3

A balanced chemical equation demonstrates conservation of mass because:

Accepted Answer

It has the same number of atoms of each element on both sides

Answer

It has the same number of molecules on both sides

Answer

It has the same number of coefficients on both sides

Answer

It has the same number of compounds on both sides

Question 4

If 4 g of hydrogen reacts with 32 g of oxygen to form water, what mass of water is produced?

Accepted Answer

36 g

Answer

28 g

Answer

32 g

Answer

40 g

Question 5

Which of the following best describes what happens to atoms during a chemical reaction?

Accepted Answer

Atoms are rearranged to form new substances

Answer

Atoms are created from energy

Answer

Atoms are destroyed to release energy

Answer

Atoms fuse together to form heavier atoms

Question 6

A student burns 12 g of carbon in excess oxygen and collects 44 g of CO₂. How much oxygen was consumed?

Accepted Answer

32 g

Answer

12 g

Answer

22 g

Answer

44 g

Question 7

Why does an open container experiment sometimes appear to violate conservation of mass when a substance burns?

Accepted Answer

Gas-phase products like CO₂ escape into the atmosphere

Answer

Mass is destroyed during combustion

Answer

The reaction creates new matter

Answer

The scale measurement is always wrong