Recent content by kbutto

I worked it out this way, is it correct? a) If only 70% of a substance remains, then the final amount y = 70%yo, and it's given that time is one year. y = 70%yo = yoe^(-k(1)) 0.70yo = yoe^(-k) 0.70 = e^(-k) k = -ln(0.70) = 0.3567 ; Half-life constant of the substance. Now use this to find...

can help me with this question :S? If 70% of a radioactive substance remains after one year, find its half-life. and Strontium-90 is a radioactive isotope with a half-life of 29 years. If you begin with a sample of 800 units, how long will it take for the amount of radioactivity of the...