What percentage of a radioactive isotope remains after 20.0 days if its half life is 10.0 days?

Brad and his family like to go camping. they always take a gas lantern with them. the lantern can take fiuels but always puts out the same amount of light. brad has two different kinds of fuel for the lantern. how can he figure out which kind of fuel has more chemical energy that the lantern can turn into light? measure the brightness of the lantern using each kind of fuel by comparing it to the full moon. g measure the volume of the containers of fuel. measure how long the lantern stays lit on a fixed amount of fuel. measure the mass of each container of fuel using a balance scale. answer 12

How many atoms of mg are present in 97.22 grams of mg? 6.022 × 1023 2.408 × 1024 4.818 × 1024 5.855 × 1025

How does the principle of electromagnetism explain the interaction between earth’s magnetic field and the solar wind?