Question

13．铀是常用的一种核燃料，若它的原子核发生了如下的裂变反应：$\left.\begin{array}{l}{235}\\{92}\end{array}\right.$U+$\left.\begin{array}{l}{1}\\{0}\end{array}\right.$n→a+b+2$\left.\begin{array}{l}{1}\\{0}\end{array}\right.$n，则a+b可能是（　　）

• A． $\left.\begin{array}{l}{140}\\{54}\end{array}\right.$Xe+$\left.\begin{array}{l}{93}\\{36}\end{array}\right.$Kr
• B． $\left.\begin{array}{l}{141}\\{56}\end{array}\right.$Ba+$\left.\begin{array}{l}{92}\\{36}\end{array}\right.$Kr
• C． $\left.\begin{array}{l}{141}\\{56}\end{array}\right.$Ba+$\left.\begin{array}{l}{93}\\{38}\end{array}\right.$Sr
• D． $\left.\begin{array}{l}{140}\\{54}\end{array}\right.$Xe+$\left.\begin{array}{l}{94}\\{38}\end{array}\right.$Sr

Answer 1

分析 根据核反应前后质量数和电荷数都守恒逐项分析即可．

解答 解：根据核反应的特点可知，核反应前后质量数和电荷数都守恒，根据各选项中的数据可知，A都不守恒，B质量数不守恒，C电荷数不守恒，D正确．
故选：D

点评 本题考查了重核裂变前后质量数和电荷数都守恒，根据两个守恒仔细计算即可，属于基础题目．