These days, the Department of Labor enforces roughly 180 worker protection laws, ranging from pay requirements to parental leave benefits. Other protections are supervised by agencies such as the U.S. Equal Employment Opportunity Commission. Below are some of the key federal protections offered to employees.
About 71 percent of the Earth's surface is water-covered, and the oceans hold about 96.5 percent of all Earth's water. Water also exists in the air as water vapor, in rivers and lakes, in icecaps and glaciers, in the ground as soil moisture and in aquifers, and even in you and your dog.
Quick Answer. Earth's atmosphere, which is around 300 miles thick, is mainly made of nitrogen and oxygen, although there are many other trace substances in its composition. Trace substances make up only 1 percent of the bulk of the atmosphere while nitrogen (78 percent), oxygen (21 percent) and argon (1 percent) make up the rest.