Question

In order for matter or energy to be conserved, one must have a ____ system.

A. open
B. closed
C. unique
D. stationary

Answer 1

closed system.  If the system is not closed, matter or energy can escape from the system.  an example of this is if you react magnesium and hydrochloric acid in a open system.  The H₂ gas is going to escape making it look like some of the mass disappeared .  in that same reaction some in an open system will also loose heat to the surrounding which will make it look like less heat was produced.

Answer 2

B. closed

Step-by-step explanation:

In an open system both matter and energy is exchanged with the surroundings. Thus option A is incorrect.

In a closed system, matter is not transferred but energy is exchanged. Option B is correct.

Isolated system does not allow the exchange of matter or energy.

Options C and D are incorrect as there are no systems in thermodynamics called unique and stationary.