What unit do scientists use to measure atoms?

Consider the nuclear equation below. 239/94 pu—-> x+ 4/2 he. what is x?

Which of the following is an example of physical change not a chemical change? a) a log gives off heat and light as it burns. b) a tree stores energy from the sun in its fruit. c) a penny lost in the grass slowly changes color. d) a water pipe freezes and cracks on a cold night.

When a scientific theory has been tested and proved by the scientific community, it becomes a law