A piece of black electrode used in dry cell on strong heating in air gave a colourless gas which turned lime -water milky. What was the material of the electrode?

We know that graphite is used for making the electrodes. So, the piece of black electrode used in the dry cell is made of graphite (which is an allotrope of carbon element). This is confirmed by the fact that the piece of electrode, on strong heating in air, gave a colourless gas carbon dioxide which turned lime- water milky. Thus, the material of the electrode is graphite.