14. About how long ago was Earth formed A. 4.5 million years C. 45 million years B. 4.5 billion years D. None of the above 15. Oceanic crust is and dense than continental crust. A. wider, less B. thinner, more C. thinner, less D. wider, more 16. Wind, solar and water are examples of resources A. nonrenewable C. fossil fuels B. budding D. renewable 17. Which cycle illustrates the path of water through the environment? A Nitrogen cycle C. Carbon cycle B. Phosphorus cycle D. Hydrologic cycle 18. What is a resource that can be replaced relatively quickly by natural processes? A. nonrenewable C. depleted resources B. material resources D.renewable resource 19. Environmental Scientists study interactions between_ A. animals and their environment. B. humans and their environments. C. humans and animals. D. animals and their habitats 20. Which of the following is the most abundant element in a Star? A. Helium C. Sulphur B. Carbon D. Hydrogen 21. Which of the following is described as a cloud of gas and dust? A. Proto star C. Black Hole B. Nebula D. Red Giant 22. What will be the next fate of a red giant after it explodes? A. It will become a planetary nebula. B. It will become a Black Hole. C. It will go back as a proto star. D. It will remain the same. 23. What do you call to the explosion of a red supergiant star? A Black Hole C. Supernova B. Planetary Nebula D. White dwarf 24. This stage of a star exerts such a string gravitational pull that no light escapes called as alan A Neutron Star C. Black Dwarf B. Protostar D. Black Hole 25. It is the earliest stage of a star's life. A. Neutron Star C. Black Dwarf B. Protostar D. Black Hole