CBSE Class 10 Answered

To call metals "noble" is a classification somehow out-of-date... it means that in the activity series of metals they are placed after the hydrogen and then, do not react with acids to form hydrogen. These metals are in order: copper,silver, mercury, platinum and gold.  Noble also could mean they are beautiful, precious, and valuable and are used to make jewlery,  mostly silver, gold and platinum. And also can mean they are very difficult to be attacted or to react chemically...like the  other metals from the  platinum group.