What is meant by surface meaning?

What concentration of salt is used to wash salad? What significant change occurred at Teotihucan? When xenon-152 undergoes alpha decay it transmutates into what? What is the plate boundary of mount Olympus? Is the majority of the earth's surface covered in water? How to turn up volume on speaker? Does global warming cause a thinning of the ozone layer? If the Sun is made of gases such as hydrogen and helium how can it have layers? Why are chloroplasts found in Elodea cells and not in the cells of a root tip? What cells are susceptible to mutation? What happens when aso titer is low? How much weight is 25 mm? What is the area rank of a country? Do obsidian rock cool quickly? How many copies of a DNA molecule result from two replication of a single DNA molecule? How do you test to see if a metal is aluminum? How was bailly crater formed? How many quarts to a half gallon how many quarts to a half a gallon? What causes magnets to attract each other at other times and repel each other at other times? What means new or previously unthought of?

What is meant by surface meaning?