\(1,\left\{{}\begin{matrix}p=e\\n+p+e=40\\2p-n=12\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}2p+n=40\\2p-n=12\end{matrix}\right.\Leftrightarrow n=\dfrac{40-12}{2}=14\)
\(2,PTK_{Al_2O_3}=2\cdot27+16\cdot3=102\left(đvC\right)\\ PTK_{Al_2\left(SO_4\right)_3}=2\cdot27+\left(32+16\cdot4\right)\cdot3=342\left(đvC\right)\\ PTK_{Fe\left(NO_3\right)_3}=56+\left(14+16\cdot3\right)\cdot3=242\left(đvV\right)\\ PTK_{Na_3PO_4}=23\cdot3+31+16\cdot4=164\left(đvC\right)\\ PTK_{Ca\left(H_2PO_4\right)_2}=40+\left(2+31+16\cdot4\right)\cdot2=234\left(đvC\right)\\ PTK_{Ba_3PO_4}=137\cdot3+31+16\cdot4=506\left(đvC\right)\\ PTK_{ZnSO_4}=65+32+16\cdot4=161\left(đvC\right)\\ PTK_{AgCl}=108+35,5=143,5\left(đvC\right)\\ PTK_{NaBr}=23+80=103\left(đvC\right)\)