Our solar system formed about 4.5 billion years ago from a dense cloud of interstellar gas and dust. The cloud collapsed most likely due to a shockwave form a nearby exploding start called a supernova
Answer:
Each row is called a period. Each column is called a group or family.
Explanation:
Mixtures can be classified as <u>homogeneous </u>or <u>heterogeneous</u>.
It is formed when water vapor condenses.
