Leta wants to know what chemical will form a precipitate with sodium chloride (nacl). leta chooses five different chemicals that she can safely mix with nacl. she then places 40 ml of nacl into 5 different beakers. finally, leta pours the different chemicals into the beakers containing nacl. leta observes what happens and records the results. what is the independent variable in leta's experiment?

20 point pls brianliest 1. what does a red shift mean? blue shift? 2. describe the big bang theory. according to this theory, how old is the universe? 3. scientists believe the universe is expanding. what is the evidence that supports this? 4. describe a nebula. 5. describe the 3 types of galaxies. what is a barred spiral galaxy? 6. what is a light year? how far is alpha centauri from earth? 7. describe the universal law of gravitation. be sure to include gravitational force between two objects. 8. describe the planets’ orbits around the sun. 9. what is the asteroid belt? where is it located? 10. describe rotation and revolution of earth. what determines an earth day and year? 11. how do galaxies exist? 12. compare and contrast the inner and outer planets. 13. what causes the seasons?