In which of the following method of purification, metal is converted to its volatite compound which is decomposed to give Pure metal'?

Vapour phase refining method includes(a) Heating of metal with stream of CO          Ni+4CO−→330-350 KNi(CO→450-470 KNi+4CO (Mond's process) (b) Heating with iodine   Zr+2I2→870 KZrI4→2075 KZr+2I2                                  Trungsten                                     filament                       (van-Arkel method)