a) Ta có: \(\left\{{}\begin{matrix}p+e+n=94\\p=e\\p+e-n=22\end{matrix}\right.\)
=> \(\left\{{}\begin{matrix}p=e=29\\n=36\end{matrix}\right.\)
=> R là Zn
b) Ta có: \(\left\{{}\begin{matrix}p+e+n=36\\p+e=2n\\p=e\end{matrix}\right.\)
=> \(\left\{{}\begin{matrix}p=e=12\\n=12\end{matrix}\right.\)
=> R là Mg
c) Ta có: \(\left\{{}\begin{matrix}p+e+n=76\\p+n=52\\p=e\end{matrix}\right.\)
=> \(\left\{{}\begin{matrix}p=e=24\\n=28\end{matrix}\right.\)
=> R là Cr
d) Ta có: \(\left\{{}\begin{matrix}p+e+n=46\\e=15\\p=e\end{matrix}\right.\)
=> \(\left\{{}\begin{matrix}p=e=15\\n=16\end{matrix}\right.\)
=> R là P
e) Ta có: \(\left\{{}\begin{matrix}p+e+n=180\\p=e\\n-p=21\end{matrix}\right.\)
=> \(\left\{{}\begin{matrix}p=e=53\\n=74\end{matrix}\right.\)
=> R là I
