What is the function of a salt bridge in a Daniell cell?

Which substance is used as cathode in a mercury cell?

The acid used in lead storage battery is

Which of the following statements are correct regarding a fuel cell that uses hydrogen and oxygen as fuels?
$A$. It has been used in spaceships.
$B$. It has an efficiency of about $40 \%$ to $60 \%$ to produce electricity.
$C$. It uses aluminium as a catalyst.
$D$. It is eco-friendly.
$E$. It is actually a type of galvanic cell.

Give true $(T)$ and false $(F)$ for the following statements:
$(1)$ In a Daniell cell,$Zn$ is dissolved in the solution and $Cu$ is deposited.
$(2)$ In a Daniell cell,when an external $1.1 \ V$ potential is applied in the opposite direction,the reaction stops and no current flows.

Which of the following is $NOT$ a difficulty in setting up a Standard Hydrogen Electrode $(SHE)$?