Ca+Cl2--->CaCl2
2K+2HNO2--->2KNO2+H2
HNO2+KOH--->KNO2+H2O
H+ +NO2- +K+ +OH- --->K+ +NO2- +H2O
H+ +OH- --->H2O
N2O3+2KOH--->2KNO2+H2O
2HNO2+K2O--->2KNO2+H2O
Fe(NO3)2+K2CO3--->FeCO3↓+2KNO3
Fe2+ +2NO3- +2K+ +CO3 2- --->FeCO3↓ +2K+ +2NO3-
Fe2+ +CO3 2- --->FeCO3↓