Câu 1:
\(a,X_2^aO_1^{II}\Rightarrow2a=II\cdot1\Rightarrow a=1\Rightarrow X\left(I\right)\\ H_2^IY_1^b\Rightarrow b=2\cdot I=2\Rightarrow Y\left(II\right)\\ CTTQ:X_c^IY_d^{II}\Rightarrow c\cdot I=d\cdot II\Rightarrow\dfrac{c}{d}=2\Rightarrow c=2;d=1\\ \Rightarrow CTHH:X_2Y\\ b,PTK_{H_2Y}=2+NTK_Y=34\left(đvC\right)\\ \Rightarrow NTK_Y=32\left(đvC\right)\\ \Rightarrow Y\text{ là lưu huỳnh }\left(S\right)\\ PTK_{X_2O}=2NTK_X+16=94\left(đvC\right)\\ \Rightarrow NTK_X=39\left(đvC\right)\\ \Rightarrow X\text{ là kali }\left(K\right)\\ c,1\left(đvC\right)=\dfrac{1}{12}\cdot m_C=\dfrac{1}{12}\cdot1,9926\cdot10^{-23}=1,6605\cdot10^{-23}\left(g\right)\\ \Rightarrow m_O=16\left(đvC\right)=16\cdot1,6605\cdot10^{-23}=2,6568\cdot10^{-22}\left(g\right)\)
Câu 2:
\(a,\) Gọi hóa trị A,B lần lượt là a,b
\(A_2^aO_3^{II}\Rightarrow x\cdot2=II\cdot3\Rightarrow x=3\Rightarrow A\left(III\right)\\ H_1^IB_1^b\Rightarrow b=I\cdot1=1\Rightarrow B\left(I\right)\\ CTTQ:A_x^{III}B_y^I\Rightarrow x\cdot III=y\cdot I\Rightarrow\dfrac{x}{y}=\dfrac{1}{3}\Rightarrow x=1;y=3\\ \Rightarrow CTHH:AB_3\\ b,PTK_{A_2O_3}=2NTK_A+48=102\left(đvC\right)\\ \Rightarrow NTK_A=27\left(đvC\right)\\ \Rightarrow A\text{ là nhôm }\left(Al\right)\\ PTK_{HB}=NTK_B+1=81\left(đvC\right)\\ \Rightarrow NTK_B=80\left(đvC\right)\\ \Rightarrow B\text{ là brom }\left(Br\right)\)
