9, Zn + 2HCl -> ZnCl2 + H2

10, 2Al + 3S -> Al2S3

11, Na2O + H2O -> 2NaOH 

12, Ca + 2C -> CaC2

13, K2O + H2O -> 2KOH

14, 2Mg + O2 -> 2MgO

15, CO2 + H2O -> H2CO3

16, S + O2 -> SO2

17, SO2 + H2O -> H2SO3

18, 2Cu + O2 -> 2CuO

19, N2O5 + H2O -> 2HNO3

Đáp án + Giải thích các bước giải:

 `9)` `Zn+2HCl` $\longrightarrow$ $ZnCl_{2}+H_2$ 

`10)` `2Al+3S` $\xrightarrow[]{t^o}Al_2S_3$

`11)` $Na_{2}O+H_2O$ $\longrightarrow 2NaOH$ 

`12)` `Ca+2C` $\xrightarrow[]{t^o} CaC_2$

`13)` $K_{2}O+H_2O$ $\longrightarrow 2KOH$ 

`14)` $2Mg+O_{2}$ $\xrightarrow[]{t^o} 2MgO$

`15)` $CO_{2}+H_2O$ $\longrightarrow H_2CO_3$ 

`16)` $S+O_{2}$ $\xrightarrow[]{t^o} SO_2$

`17)` $SO_{2}+H_2O$ $\longrightarrow H_2SO_3$ 

`18)` $2Cu+O_{2}$ $\xrightarrow[]{t^o} 2CuO$

`19)` $N_{2}O_5+H_2O$ $\longrightarrow 2HNO_3$