The acid used in lead storage battery is

$A$ saturated solution of $KNO_3$ with agar-agar is used to make a 'salt-bridge' because

Which of the following statements is true for a standard electrochemical cell consisting of $H_2$ and $Cu$ electrodes?

What is the change in oxidation number of $Pb$ at the positive electrode of a lead accumulator acting as a galvanic cell?

Which of the following reactions occurs at the cathode during the charging of a lead storage battery?

Four different solutions are placed in separate beakers,and a copper metal strip is added to each. Which solution will turn blue after some time?