\(a.\)
\(CT:P_2O_y\)
Ta có :
\(\dfrac{31\cdot2}{16y}=\dfrac{0.775}{1}\)
\(\Rightarrow y=5\)
\(CTPT:P_2O_5\) ( diphotpho pentaoxit)
\(b.\)
\(n_{P_2O_5}=\dfrac{28.4}{142}=0.2\left(mol\right)\)
\(P_2O_5+3H_2O\rightarrow2H_3PO_4\)
\(0.2........................0.4\)
\(C_{M_{H_3PO_4}}=\dfrac{0.4}{0.3}=1.33\left(M\right)\)


