作者def2864 (def2864)
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标题[试题] 97下 林万寅 普通化学甲 第六次小考
时间Tue Jun 30 21:35:41 2009
课程名称︰普通化学甲
课程性质︰必修
课程教师︰林万寅
开课学院：理学院
开课系所︰物理系
考试日期（年月日）︰09.06.03
考试时限（分钟）：15min
是否需发放奖励金：是
（如未明确表示，则不予发放）
试题 :
1. (236 88)Ra undergoes α-decay to give radon nucleus with a half-life of 1600
years. The mass of each Ra-226 is 226.025402 u and 1u = 1.67*10^-24g 12%
(a) Write the nuclear reaction for the decay of Ra-226 to Rn.
(b) Find the decay constant k for the first-order decay of Ra-226
(c) Calculate the radioactivity (in Becquerel or disintegrations/s) of 1.00g
Ra-226
(d) What volume of Radon (Rn-222) will be produced per day at STP from 1.00g of
Ra-226?
2. A rock contains 280μmol (238 92)U (t1/2 = 4.5*10^6 yr) and 120μmol
(206 82)Pb. Assume that all the Pb-206 comes from decay of U-238 8%
(a) Estimate the age of the rock.
(b) How many α and β decays are involved in the decay series of U-238 to
Pb206?
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