Aulfur does not conduct electricity.

Mercury is, in fact, a metal which conducts electricity just like other metals.

are concentrated solutions all aqueous? as i have a qn which says "what changes take place when concentrated potassium chlorine solution is electrolysed using inert electrodes"
they did not specify whether the solution is aqueous or molten...

Concentrated is still aqueous, but is usually treated differently from dilute. Think of dissolving two or three spoons of Milo powder to a glass of warm water versus dissolving an entire large tin of Milo powder to the same volume of warm water.

if they said copper(II) chloride solution, do we take it as molten or aqueous? they did not specify whether its concentrated, molten or aqueous

“Solution” usually refers to dilute aqueous solutions, unless otherwise stated.

Imagine being served a “Milo drink” and then you suddenly realise that the Milo concentration is too high as you drink it.

Which is why usually solutions are dilute.

Note for the O-levels, the following phrasing is used:
Concentrated aqueous = concentrated solution.

Dilute (...) or simply (....) solution = dilute solution.

Recall that preferential discharge of halide ions (iodide easiest, then bromide, then chloride) over hydroxide occurs for concentrated aqueous solutions, at the anode (positive electrode).

Solutions refer to a solute such as a salt, dissolved in water.

thx :)

how to identify which metal electrode belong to the postive and negative terminal tho

for example Pb and Fe electrodes, which one will be the postive and negative terminal

Assuming you are referring to a simple cell: the negative electrode is always the more reactive metal, in your example, its Fe. Fe --> Fe2+ + 2 e

Iron becomes oxidised to iron(II) ions. Electrons loss by iron move through the external circuit (conducting wire) to the Pb electrode (positive electrode).