After three half-lives, what fraction of a radioactive sample has decayed

5/6
1/2
7/8
2/3

Write the correct abbreviation for each metric unit

The built in flash in a compact camera is usally capable of giving correct exsposure for distance up to how many meters?

Atemperature inversion can cause a warm air mass to move over a colder air mass. this traps the colder air mass and prevents surface air from rising. this may result in which of these? a) smog b) acid rain c) freezing rain d) a thunderstorm