Which of the following statements is true?

boiling and melting points are chemical properties.
a molecule of oxygen can have atoms of carbon in it.
elements are substances made of only one type of atom.
the number of electron shells in an atom is called the atomic number.

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.