B. Fill a large beaker half full of water. Add two or three drops of ink to the water. Insert a test tube open end down. The water does not enter the test tube because air occupies the space. Tilt the tube so that some air escapes.
Water now enters to occupy the space vacated by the air.
C. Wave about and collect air in a plastic bag. Quickly close the bag and tie the end with a twist tie. Place the bag on a table top and balance a book on top of the bag. D. Mold some clay around the neck of a funnel. Press the funnel into the mouth of a jug so that an airtight seal is created.