Bài 2:

\(\left\{{}\begin{matrix}P+E+N=52\\P=E=Z=\\\left(P+E\right)-N=16\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}2P+N=52\\2P-N=16\end{matrix}\right.\\ \Leftrightarrow\left\{{}\begin{matrix}P=E=Z=17\\N=18\end{matrix}\right.\)

Bài 1:

\(\left\{{}\begin{matrix}P=E=Z\\Z^+=13^+\\\left(P+E\right)-N=12\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}P=E=Z=13\\2P-N=12\end{matrix}\right.\\ \Leftrightarrow\left\{{}\begin{matrix}P=E=Z=13\\N=14\end{matrix}\right.\\ \Rightarrow A_{Al}=Z+N=13+14=27\left(đ.v.C\right)\)

Em ơi câu hỏi đâu rồi nè?

\(n_{Na_2O}=\dfrac{6,2}{62}=0,1\left(mol\right)\\ Na_2O+H_2O\rightarrow2NaOH\\ C_{MddA}=C_{MddNaOH}=\dfrac{0,2}{0,4}=0,5\left(M\right)\)