Bài 1:
a, $NaCl$
b, $m_{NaCl}=200.0,9\%=1,8g$
Bài 2:
a, $2KMnO_4\buildrel{{t^o}}\over\to K_2MnO_4+MnO_2+O_2$
b, $Fe+2HCl\to FeCl_2+H_2$
c, $2H_2O\buildrel{{đpdd}}\over\to 2H_2+O_2$
d, $P_2O_5+3H_2O\to 2H_3PO_4$
e, $2Zn+O_2\buildrel{{t^o}}\over\to 2ZnO$