<P> Fountain pen nibs made from gold are sometimes plated with palladium when a silver (rather than gold) appearance is desired . Sheaffer has used palladium plating for decades, either as an accent on otherwise gold nibs or covering the gold completely . </P> <P> In the platinotype printing process, photographers make fine - art black - and - white prints using platinum or palladium salts . Often used with platinum, palladium provides an alternative to silver . </P> <P> Palladium is a metal with low toxicity . It is poorly absorbed by the human body when ingested . Plants such as the water hyacinth are killed by low levels of palladium salts, but most other plants tolerate it, although tests show that, at levels above 0.0003%, growth is affected . High doses of palladium could be poisonous; tests on rodents suggest it may be carcinogenic, though no clear evidence indicates the element harms humans . </P> <P> Like other platinum - group metals, bulk Pd is quite inert . Although contact dermatitis has been reported, data on the effects are limited . It has been shown that people with an allergic reaction to palladium also react to nickel, making it advisable to avoid the use of dental alloys containing palladium on those so allergic . </P>

Which of the following are most chemically similar to pd