An original sample of the radioisotope fluorine-21 had a mass of 80. 0 milligrams. Only 20. 0 milligrams of this original sample remain unchanged after 8. 32 seconds. What is the half-life of fluorine-21?.

The occupational safety and health administration requires employers to provide fall protection to construction workers who are working on surfaces with unprotected sides and edges feet or greater above the lower level.

Asoccer team has played 25 games and has won 60% of the games it has played. what is the minimum number of additional games the team must win in order to finish the season winning 80% of the games it has played?

The smokey mountains have over 2,100 miles of rushing mountain streams and rivers that flow through the park. in each mile lives a diverse community of native fish, amphibians, insects, and larvae, some of which are found only in the southern appalachians. park managers and scientific researchers test many factors such as fish populations, the watersheds and water tests to determine a) too many lizards are present b) the water quality of the stream c) rainwater is running into local streams d) if visitors to the park are overstaying their welcome