How is mechanical weathering different from chemical weathering? a
Chemical weathering happens over a much shorter time frame than mechanical weathering.

b
Chemical weathering happens in the tropics; mechanical weathering occurs in temperate climates.

c
Chemical weathering happens in mountains; mechanical weathering happens on flat surfaces.

d
Chemical weathering changes the chemical makeup of materials; mechanical weathering doesn't.

in scientific notation, the value of the  speed of light in a vacuum

  will be written as 2.995 * 10^8. when this value is represented in the form of

  a * 10^b, then, a = 2.995 and b = 8.

the value of the speed of light in a vacuum given above can also be rounded up to approximately 300000000. in this case, the scientific notation will be written as 3 *10^8.

metric time was an attempt to create a standard unit of time based off of 10, but it never took off an is not included in the metric system (si)