Is the size of an atom larger or smaller then a grain of sand

What metric units would you use to measure the thickness of a key

State one important difference between a physical change and a chemical change?

Which of these is an example of pseudoscience? a) predicting the time of sunrise based on data on position of earth b) predicting the date of the moon phases based on data on position of earth c) predicting eclipses based on the position of the sun and the moon d) predicting future events in a person's life based on the position of the moon