ANS:D - all (a), (b) & (c).

The statement "Electrolytic refining of blister copper is resorted to when there is a demand for ultrapure (99.99%) electrolytic copper" is correct. Electrolytic refining of blister copper is a common method used to purify copper to a very high degree of purity, typically 99.99% or higher. This process involves passing an electric current through a solution containing copper ions, which causes the copper to deposit onto a cathode as pure copper metal while impurities are left behind in the electrolyte or settle as sludge. Here's why electrolytic refining is used:

1. High Purity Requirement: Electrolytic refining is used when there is a demand for ultrapure copper, such as in electronic and electrical applications where even minute impurities can impair electrical conductivity. The process allows for the removal of impurities to achieve the desired purity level.
2. Selective Deposition: During electrolytic refining, only copper ions are selectively deposited onto the cathode, while impurities remain in the electrolyte or settle out as sludge. This selective deposition ensures that the final product is highly pure copper with minimal impurities.
3. Precious Metal Recovery: In addition to purifying copper, electrolytic refining can also recover precious metals such as gold, silver, and platinum that may be present in the blister copper feedstock. These precious metals are deposited alongside the copper and can be recovered from the cathode sludge.