what is the noble metal ?

The noble metal catalyst

In chemistry, the noble metals are metals that are aggressive to bane and blaze in clammy air (unlike a lot of abject metals). The abbreviate account of chemically noble metals (those elements aloft which about all chemists agree) comprises ruthenium, rhodium, palladium, silver, osmium, iridium, platinum, and gold.
The noble metals are metals that are aggressive to bane and blaze in clammy air, clashing a lot of abject metals. They tend to be precious, generally due to their aberration in the Earth's crust.
More across-the-board lists cover one or added of mercury,rhenium or chestnut as noble metals. On the added hand, titanium, niobium, and tantalum are not included as noble metals although they are actual aggressive to corrosion.