Large radioactive atoms decay into smaller atoms by releasing alpha particles. Each alpha particle has 2 protons, 2 neutrons, and 0 electrons. The table below describes several neutral, low-mass atoms.
\begin{tabular}{|l|l|l|l|}
\hline \multicolumn{4}{|c|}{ Stable Isotopes of Low-Mass Elements } \\
\hline Element Name & Symbol & \begin{tabular}{l} Atomic \\ Number \end{tabular} & \begin{tabular}{l} Number of \\ Neutrons \end{tabular} \\
\hline Hydrogen & H & 1 & 0 \\
\hline Helium & He & 2 & 2 \\
\hline Lithium & Li & 3 & 4 \\
\hline Berylium & Be & 4 & 5 \\
\hline
\end{tabular}
An alpha particle is also referred to as a nucleus of which isotope?
A. lithium-7
B. helium-4
Answer (3)
222 ;
2 x + 4 y = − 4 ( / ∗ 3 ) 3 x + 5 y = − 3 ( / ∗ ( − 2 )) ⇒
6 x + 12 y = − 12 − 6 x − 10 y = 6 ⇒
2 y = − 6 ⇒ y = − 3 y = − 3 ⇒ 2 x + 4 y = − 6 → 2 x + 4. ( − 3 ) = − 6 ⇒ 2 x − 12 = − 6 ⇒ 2 x = 6 ⇒ x = 3
( x , y ) = ( 3 , − 3 )
To solve the system 2 x + 4 y = − 4 and 3 x + 5 y = − 3 using elimination, we scaled the equations to eliminate x and found y = − 3 . Substituting back gives us x = 4 . The final solution is ( x , y ) = ( 4 , − 3 ) .
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