Aglass flask containing 100 milliliters of water is sealed with a rubber stopper and placed on a burner. after a while, gas condenses on the inside surface of the flask near the stopper. what type of system is this an example of?

a closed system, because energy can enter or leave the container, but the water molecules cannot.
an open system, because heat and the water are both being exchanged between the container and the surroundings.
an isolated system, because heat and matter can enter but cannot leave the system.
an isolated system, because energy can enter or leave the system, but matter can only move in one direction.

A closed system, because energy can enter or leave the container, but the water molecules cannot

Explanation:

According to question, the system given is a closed system.This is because energy is transferred from the burner to glass flask and from the glass flask to the water (matter).

But no water molecule is coming outside the flask instead of that they are getting condensed on the inside surface of the glass flask which means that matter is not allowed to move beyond the boundaries of the system.

Where as in open system both matter and energy are allowed to move beyond the boundaries of the system.

In an isolated system both energy and matter are not allowed to move beyond the boundaries of the system.