Final answer:
The statement about a pebble creating a pulse wave is true, and a solar sail craft can be propelled by solar wind particles.
Step-by-step explanation:
If you expel air underwater, you will indeed create bubbles. This is true because when air is expelled, it is less dense than the surrounding water, which causes it to rise to the surface in the form of bubbles. This is similar to what happens when a bottle of sparkling water is opened; the carbon dioxide forms bubbles and escapes into the atmosphere. Scuba divers also experience this when they breathe out while underwater; their expelled breath forms bubbles which ascend to the surface due to the buoyant force.
In the case of a pebble dropped in water, it creates ripples on the surface, which is an example of a pulse wave; this would make that statement true. Furthermore, the concept of a solar sail craft being propelled by particles within the solar wind is also true, as solar sails use the momentum of photons or solar wind particles to propel spacecraft through space.