RPAL Conservation of Mass 2

Question 1

In the reaction N₂ + 3H₂ → 2NH₃, if 28 g of N₂ reacts with 6 g of H₂, what mass of NH₃ is produced?

Accepted Answer

34 g

Answer

17 g

Answer

28 g

Answer

40 g

Question 2

Which quantity is always equal before and after a chemical reaction in a closed system?

Accepted Answer

Total mass

Answer

Number of molecules

Answer

Number of moles

Answer

Volume of substances

Question 3

A reaction produces 18 g of water and 44 g of CO₂ from methane and oxygen. If 16 g of methane was used, how much oxygen was consumed?

Accepted Answer

46 g

Answer

26 g

Answer

32 g

Answer

62 g

Question 4

Conservation of mass requires that a chemical equation must be:

Accepted Answer

Balanced

Answer

Unbalanced

Answer

Written with whole number subscripts only

Answer

Written with the same number of compounds on each side

Question 5

If 50 g of reactants are placed in a sealed, rigid container and a reaction occurs, what is the mass of the products?

Accepted Answer

Exactly 50 g

Answer

Less than 50 g

Answer

More than 50 g

Answer

It depends on the type of reaction

Question 6

When iron rusts, it gains mass. This is consistent with conservation of mass because:

Accepted Answer

The iron absorbs oxygen from the air, adding to the total mass

Answer

Mass is created during oxidation

Answer

Some energy converts to mass

Answer

The density increases, so mass increases

Question 7

In a decomposition reaction, CaCO₃ → CaO + CO₂, 100 g of CaCO₃ decomposes to give 56 g of CaO. What mass of CO₂ is released?

Accepted Answer

44 g

Answer

56 g

Answer

100 g

Answer

144 g