Question

X+hcl—y+h2o
X+h2o—koh
Ca(oh)2+x—caco3+y
H2o+x—h2so4

Answer 1

KOH+HCl = KCl+H2O
K2O+H2O=2KOH
Ca(OH)2+CO2=CaCO3+H2O
H2O+SO3=H2SO4