how do you know that a chemical has happened? A: A substance is mixed with water and forms a solution. B: The substance increases in temperature. C: The substance changes its state. D:A new substance forms. *It didn't say science so I put it as chemistry but its science sorry​

Which of these statements best explains why space exploration should be encouraged? it prepares humans to live without oxygen. it dispel myths about objects in space. it prevents comets and asteroids from striking earth. it creates technology to absorb harmful radiations in space.