a. PTHH: \(2Mg+O_2\underrightarrow{t^o}2MgO\\ 0,25mol:0,125mol\rightarrow0,25mol\)
\(n_{Mg}=\dfrac{6}{24}=0,25\left(mol\right)\)
\(m_{MgO}=0,25.40=10\left(g\right)\)
b. PTHH: \(2KClO_3\xrightarrow[t^o]{MnO_2}2KCl+3O_2\\ 0,1mol\leftarrow0,1mol:0,15mol\)
\(n_{O_2candieuche}=0,125+\left(0,125.20\%\right)=0,15\left(mol\right)\)
\(m_{KClO_3}=0,1.122,5=12,25\left(g\right)\)