Equation mistakes... ? ?

Question

Can anyone explain why the following equations are wrong please?

C2H4(g) + 2O2(g) --> 2CO2(g) + 2H2(g)

Cu(s) + H2SO4(aq) --> CuSo4 (aq) + H2(g)

NaCo3 + 2HCl(aq) --> NaCl2(aq) + CO2(g) + H2O(l)

Thank you !

Answer 1

Copper doesn't react with dilute acids. So although the eqn is balanced,it is not true.

Answer 2

C2H4(g) +3 O2 (g)>> 2CO2(g) + 2H2O (g)

no reaction

Na2CO3(aq) + 2 HCl (aq)>> H2O (l)+ CO2 (g) + 2 NaCl (aq)