Дано:
\\ (El) =1-0.2 = 0.8 \\ A_r(O) = 16 \\ \\ (O) = \frac{A_r (O) * y}{M_r(El_xO_y)} = 0.2 \\ (El) = \frac{A_r (El) * y}{M_r(El_xO_y)}=0.8 \\ \frac{(El)}{(O)} = \frac{(0.8)}{(0.2)} = 4 \\ \\ \frac{( \frac{A_r (El) * x}{M_r(El_xO_y)})}{(\frac{A_r (O) * y}{M_r(El_xO_y)} )} = 4 <=> \frac{A_r (El) * x}{A_r (O) * y} = 4 \\ A_r (El) =4*(y/x)*A_r(O) = 4*16*(y/x)" alt="El_xO_y \\ (O)=20 \%\ \\ ------- \\ El - ? \\ ------- \\ (O)=20 \%\ =0.2 => \\ (El) =1-0.2 = 0.8 \\ A_r(O) = 16 \\ \\ (O) = \frac{A_r (O) * y}{M_r(El_xO_y)} = 0.2 \\ (El) = \frac{A_r (El) * y}{M_r(El_xO_y)}=0.8 \\ \frac{(El)}{(O)} = \frac{(0.8)}{(0.2)} = 4 \\ \\ \frac{( \frac{A_r (El) * x}{M_r(El_xO_y)})}{(\frac{A_r (O) * y}{M_r(El_xO_y)} )} = 4 <=> \frac{A_r (El) * x}{A_r (O) * y} = 4 \\ A_r (El) =4*(y/x)*A_r(O) = 4*16*(y/x)" align="absmiddle" class="latex-formula">
Отсюда
Ar(O) = 64 * (x/y)
Возможные варианты индексов оксида:
El_2O\ (x=2; y=1);\ y/x=0.5 \\ A_r(El)=64*0.5=32;\ El-S; S_2O - !not \\ El^+^2 <=> ElO\ (x=1; y=1);\\ y/x=1 A_r(El)=64; El-Cu;\ CuO- \exists \\ El^+^3 <=> El_2O_3\ (x=2; y=3);\\ y/x=1.5 A_r(El)=64*1.5=96;\ El-Mo;\ Mo_2O_3 \ - \exists\\ El^+^4 <=> ElO2\ (x=1; y=2);\\ y/x=2 A_r(El)=64*2=128;\ Not El \\ El^+^5 <=> El_2O_5\ (x=2; y=5);\\ y/x=2.5 A_r(El)=64*2.5=160;\ El-Tb;\ Tb_2O_5\ - not\ info \\ El^+^6 <=> ElO_3\ (x=1; y=3);\\ y/x=3 A_r(El)=64*3=192 El - Ir;\ IrO3\ - \exists " alt="x,y: \\ El^+^1 <=> El_2O\ (x=2; y=1);\ y/x=0.5 \\ A_r(El)=64*0.5=32;\ El-S; S_2O - !not \\ El^+^2 <=> ElO\ (x=1; y=1);\\ y/x=1 A_r(El)=64; El-Cu;\ CuO- \exists \\ El^+^3 <=> El_2O_3\ (x=2; y=3);\\ y/x=1.5 A_r(El)=64*1.5=96;\ El-Mo;\ Mo_2O_3 \ - \exists\\ El^+^4 <=> ElO2\ (x=1; y=2);\\ y/x=2 A_r(El)=64*2=128;\ Not El \\ El^+^5 <=> El_2O_5\ (x=2; y=5);\\ y/x=2.5 A_r(El)=64*2.5=160;\ El-Tb;\ Tb_2O_5\ - not\ info \\ El^+^6 <=> ElO_3\ (x=1; y=3);\\ y/x=3 A_r(El)=64*3=192 El - Ir;\ IrO3\ - \exists " align="absmiddle" class="latex-formula">
Итого - три элемента удовлетворяют условию задачи.
Насчет существования Tb2O5 - у меня нет информации.