One beneficial use of radioisotopes is
(1) detection of disease
(2) neutralization of an acid spill
(3) decreasing the dissolved o2(g) level in seawater
(4) increasing the concentration of co2(g) in the atmosphere

(1) detection of disease

There are numbers of things that the radioisotopes do but for this one is Detection.  Its almost like a scope like or tool to see what's the problem deep inside.  Ex. different types of gases on your skin.

pure water does not conduct electricity very well. however, when certain substances are dissolved in water, the solution does conduct electricity. you can make a simple device that shows how well a solution conducts electricity. this device uses a flashlight bulb to indicate how well the solution conducts electricity. the better the solution conducts electricity, the brighter the bulb will glow.

explanation: