Question

removing heat from a system changes the internal energy of the system. which scenario correctly represents this case?
a placing a bowl of ice cubes in a closed room
b adding ice cubes into a thermos of hot coffee
c switching on the air conditioning of a closed room
d placing a thermos with hot coffee in an air conditioned room

Explanation:

Removing heat from a system decreases its internal energy. Ice cubes absorb heat from their surroundings to melt. In option A, ice cubes in a closed room will absorb heat from the room (the system here is the room), reducing the room's internal energy. Option B: A thermos minimizes heat transfer, so ice melting won’t significantly remove heat from the coffee system. Option C: AC adds cool air but doesn’t involve heat removal via ice absorption. Option D: A thermos keeps coffee hot, no heat removal.

Answer:

A. placing a bowl of ice cubes in a closed room