A phase change is a physical change.
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Answer:
A. to cure human diseases
Explanation:
Answer:
As you go down group 1, the number of electron shells increases – lithium has two, sodium has three, and so forth. The attraction from the positive nucleus to the negative electron is less. This makes it easier to remove the electron and makes the atom more reactive.
People have thought that everything had went around the earth Our understanding of the universe has changed over time. Different civilizations have created different models to explain what the universe
is and how the universe began. The Greek astronomer Ptolemy
used measurements of the sky to create his geocentric model. This had the earth at the center and all the planets and the sun orbiting around it.
