An example of a physical change
is liquid water turning into vapor. Physical change is that it may involve a
change in phase but does not involve a change in molecular structure.
Answer:
7.5 pounds per square-inch
At sea level, one square-inch of any surface has about 15 pounds of air sitting on top of it. At 18,000 feet, that same square inch has only 7.5 pounds per square-inch (psi) exerted on it.
I believe the answer is F
Lithium, Sodium, Potassium; any of the Alkali Metals, which are farthest left on the periodic table. This is because they only have one electron in their outermost shell, so they would rather lose an electron rather than try to gain 7 to achieve that full outer shell.