Question

Which chemical equation is balanced?

Answer 1

The balanced chemical equation among the given equations is:
${\mathrm{CaCO}}_3\to \mathrm{CaO}+{\mathrm{CO}}_2$
The other equations can be balanced as:
$2H_2{O}_2\to 2H_{2}O+O_{2}2{\mathrm{NaNO}}_3\to 2{\mathrm{NaNO}}_2+O_2{\mathrm{Al}}_2{\left({\mathrm{CO}}_3\right)}_3\to {\mathrm{Al}}_2{O}_3+3{\mathrm{CO}}_2$