Question

The radioactive isotope thorium 234 has a half-life of approximately 578 hours. (a) If a sample has a mass of 67 milligrams, find an expression for the mass after t hours. Q(t) = 67e-0.0011997 (b) How much will remain after 85 hours? (Round your answer to one decimal place.) 60.5 mg (c) When will the initial mass decay to 20 milligrams? (Round your answer to one decimal place.) 1008.3 x hr

Answer 1

Please refer to the pics.

As (a) & (6) are soreed Î will focus on (C). Given. Thorium 234 has a half life The radioactive isotope of 578 hours. OY - -xt No e N(t) = Equation is, N(t) Nollants No is initial quantity S alle where Nt is remaining Net) - Noe quantity after timet ty is half life e is mean life time * is decay constant. (a) Giren Sample has a mass of 67 mg. After thours, Ro = 67 my Qlt) = 80(%) 573. 67 x(13)/578 -0.001199 + As 1+ y = lima , tese d= -0.001lagt.Ccalculated). : 67 e (6) After 85 hours, 85/578 = (85) = 67X/I 60.5 mg

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