Which of the Following Reactions Is an Example of Positron ${ }_{91}^{227} \mathrm{~Pa} \rightarrow{ }_{89}^{223} \mathrm{Ac}+{ }_{2}^{4} \mathrm{He}$

question 24

Multiple Choice

Which of the following reactions is an example of positron emission?

• A) \({ }_{91}^{227} \mathrm{~Pa} \rightarrow{ }_{89}^{223} \mathrm{Ac}+{ }_{2}^{4} \mathrm{He}\)
• B) \({ }_{20}^{41} \mathrm{Ca}+{ }_{-1}^{0} e \rightarrow{ }_{19}^{41} \mathrm{~K}\)
• C) \({ }_{79}^{201} \mathrm{Au} \rightarrow{ }_{80}^{201} \mathrm{Hg}+{ }_{-1}^{0} \mathrm{\beta}\)
• D) \({ }_{63}^{150} \mathrm{Eu} \rightarrow{ }_{62}^{150} \mathrm{Sm}+{ }_{+1}^{0} \beta\)
• E) \({ }_{26}^{58} \mathrm{Fe}+{ }_{0}^{1} n \rightarrow{ }_{26}^{59} \mathrm{Fe}\)

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A situation where a country's exports exceed its imports over a given time period, reflecting a positive balance of trade.

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The unequal ratio of domestic purchases of overseas assets to foreign purchases of domestic assets.