After 32 days, 5 milligrams of an 80-milligram sample of a radioactive isotope remains unchanged. what is the half-life of this element?
(1) 8 days (3) 16 days
(2) 2 days (4) 4 days

The speed of light is around 6.706×10^8 miles per hour. what is the speed of light in units of miles per minute?

What layer of the atmosphere is directly above the troposphere?

Calculate the ratio of h+ ions to oh– ions at a ph = 7. find the concentration of h+ ions to oh– ions listed in table b of your student guide. then divide the h+ concentration by the oh– concentration. record this calculated ratio in table a of your student guide. compare your approximated and calculated ratios of h+ ions to oh– ions at a ph = 7. are they the same? why or why not? record your comparison in table a. what is the concentration of h+ ions at a ph = 7? mol/l what is the concentration of oh– ions at a ph = 7? mol/l what is the ratio of h+ ions to oh– ions at a ph = 7? : 1