What is the difference among the following chemical combination reactions ?
1) 2H2 + O2 → 2H2O
2) 2CO + O2 → 2CO2
3) NH3 + HCl → NH4Cl
A) In reactants of first equation both are elements.
B) In reactants of second equation one is compound and other one is element.
C) In equation three both the reactants are compounds.
D) All are correct.
