In a dry cell,which element acts as the negative electrode?

Which of the following statements is true for an electrolytic cell?

$Zn_{(s)} | Zn^{2+}_{(aq)} || Cu^{2+}_{(aq)} | Cu_{(s)}$ is

How is the complete external and internal path completed for electron flow for a galvanic cell? Clarify it.

An aqueous solution of hydrazine $(N_2H_4)$ is electrochemically oxidized by $O_2$,thereby releasing chemical energy in the form of electrical energy. One of the products generated from the electrochemical reaction is $N_{2(g)}$.
Choose the correct statement$(s)$ about the above process:
$A$. $OH^{-}$ ions react with $N_2H_4$ at the anode to form $N_{2(g)}$ and water,releasing $4$ electrons to the anode.
$B$. At the cathode,$N_2H_4$ breaks to $N_{2(g)}$ and nascent hydrogen released at the electrode reacts with oxygen to form water.
$C$. At the cathode,molecular oxygen gets converted to $OH^{-}$.
$D$. Oxides of nitrogen are major by-products of the electrochemical process.

$Zn_{(s)} | Zn_{(aq)}^{2+}(1 \ M) || Ni_{(aq)}^{2+}(1 \ M) | Ni_{(s)}$
Which is incorrect for the given cell?