Which colourless gas evolves,when $NH_4Cl$ reacts with zinc in a dry cell battery?

The cell reaction of the galvanic cell $Cu_{(s)} | Cu^{2+}_{(aq)} || Hg^{2+}_{(aq)} | Hg_{(l)}$ is

Zinc displaces copper from the solution of its salt because

Which of the following metals will not react with a solution of $CuSO_4$?

The standard cell potential $(E_{\text{cell}}^{\ominus})$ of a fuel cell based on the oxidation of methanol in air that has been used to power television relay station is measured as $1.21 \ V$. The standard half-cell reduction potential for $O_2$ $(E_{O_2 / H_2 O}^0)$ is $1.229 \ V$. Choose the correct statement:

In a galvanic cell,the salt bridge