\(\overline{M_{bđ}}=15,2.2=30,4\)
\(n_{bđ}=\frac{1,12}{22,4}=0,5\left(mol\right)\)
\(\left\{{}\begin{matrix}n_{O2}:a\left(mol\right)\\n_{N2}:b\left(mol\right)\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}a+b=0,5\\\frac{32a+28b}{0,5}=30,4\end{matrix}\right.\)
\(\Rightarrow\left\{{}\begin{matrix}a=0,3\\b=0,2\end{matrix}\right.\)
\(\overline{M_{dư}}=30\)
\(n_{O2\left(dư\right)}=x\left(mol\right)\)
\(\Rightarrow\frac{32x+28.0,2}{x+0,2}=30\)
\(\Rightarrow x=0,2\)
\(n_{O2\left(pư\right)}=0,3-0,2=0,1\left(mol\right)\)
\(4Y+O_2\rightarrow2Y_2O\)
0,4____0,1______
\(\Rightarrow M_Y=\frac{15,6}{0,4}=39\left(K\right)\)