Question

why gold is called a nobel metal

Answer 1

Because it is very expensive and hard to find!!

Answer 2

Hey Friend here's the answer to your question

Platinum and gold dissolve in the acid solution aqua regia. On the other side not all corrosion-resistant metals are considered to be noble metals. ... They are unreactive ie they resist corrosion and other chemical attack - hence why they are mostly found in their elemental states and not oxides