## Chemistry and Chemical Reactivity (9th Edition)

A) Changes in the oxidation number: $Zn/Zn^{2+}$: $Zn :0\rightarrow+2$ $NO_3^-/NO_2$: $N :+5\rightarrow+4$ B) No changes in oxidation numbers. C) Changes in the oxidation number: $Ca/Ca(OH)_2$: $Ca: 0\rightarrow+2$ $H_2O/H_2$: $H: +1\rightarrow0$