3.

Xét `n_M=1(mol)`

`M+CuSO_4->MSO_4+Cu(1)`

`M+2AgNO_3->M(NO_3)_2+2Ag(2)`

Theo PT: `n_{Cu}=n_M=1(mol);n_{Ag}=2n_M=2(mol)`

`\Delta m_1=m_M-m_{Cu}=m_M-64(g)`

`\Delta m_2=m_{Ag}-m_M=216-m_M(g)`

`->{m_M-64}/{216-m_M}={0,1}/{15,1}`

`->m_M=65(g)`

`->M_M={65}/1=65(g//mol)`

`->M` là zinc `(Zn).`

5.

Xét `x=1`

`->y=7-1=6`

\(\to B:\ 1s^22s^22p^63s^23p^6\) là khí hiếm `Ar` loại.

Xét `x=2`

`->y=7-2=5`

\(\to B:\ 1s^22s^22p^63s^23p^5\) nhận.

\(\to A:\ 1s^22s^22p^63s^2\)

`->B` là chlorine `(Cl)` và `A` là magnesium `(Mg).`

7.

`A:\ CH_4`

`B:\ C_2H_2`

`C:\ C_2H_4`

`D:\ C_2H_5OH`

`E:\ CH_2=CH-CH=CH_2`

`F:\ CH_2=CH-Cl`

`----------`

`(1)2CH_4`  $\xrightarrow[LLN]{1500^oC}$  `C_2H_2+3H_2`

`(2)C_2H_2+H_2`  $\xrightarrow{t^o,Lindlar}$  `C_2H_4`

`(3)C_2H_4+H_2O`  $\xrightarrow{t^o,H^+}$  `C_2H_5OH`

`(4)2C_2H_5OH`  $\xrightarrow{t^o,xt}$  `CH_2=CH-CH=CH_2+H_2+2H_2O`

`(5)nCH_2=CH-CH=CH_2`  $\xrightarrow{t^o,p,xt}$  $(\kern-6pt- CH_2-CH=CH-CH_2 -\kern-6pt)_n$

`(6)C_2H_2+HCl`  $\xrightarrow{t^o,HgCl_2}$  `CH_2=CH-Cl`

`(7)nCH_2=CH-Cl`  $\xrightarrow{t^o,p,xt}$ $(\kern-6pt- CH_2-CH(Cl)-\kern-6pt)_n$

`(8)nCH_2=CH_2`  $\xrightarrow{t^o,p,xt}$ $(\kern-6pt- CH_2-CH_2-\kern-6pt)_n$