To answer this, all you have to do is take the mass of the sample, in grams, and divide it by the atomic/molecular mass of the substance, in amu (atomic mass units)
So, here are my answers:
(i) 53g of Palladium = 53/106 = 0.5 moles
(ii) 216g of Silver = 216/108 = 2 moles
(iii) 46g of Tungsten = 46/184 = 0.25 moles
Hope I helped!! xx