Question

13．鈾是常用的一種核燃料，若它的原子核發生了如下的裂變反應：$\left.\begin{array}{l}{235}\\{92}\end{array}\right.$U+$\left.\begin{array}{l}{1}\\{0}\end{array}\right.$n→a+b+2$\left.\begin{array}{l}{1}\\{0}\end{array}\right.$n，則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 根據核反應前后質量數和電荷數都守恒逐項分析即可．

解答 解：根據核反應的特點可知，核反應前后質量數和電荷數都守恒，根據各選項中的數據可知，A都不守恒，B質量數不守恒，C電荷數不守恒，D正確．
故選：D

點評 本題考查了重核裂變前后質量數和電荷數都守恒，根據兩個守恒仔細計算即可，屬于基礎題目．