Condition like heat should be mentioned and the state of reactants and products should be given.
For Example :
CaCO3(s)heat−−−→CaO(s)+CO2(g)
What information does the following chemical equations convey ?
(a) Zn + H2SO4 → ZnSO4 + H2
(b) Mg + 2HCl → MgCl2 + H2