Answer
$1.59 g\ Pt$
Work Step by Step
1. Use Avogadro's number and the molar mass of platinum as conversion factors in order to determine the number of grams of platinum in the sample.
2. $(4.91 \times 10^{23}atoms\ Pt) \times \frac{1 molPt}{6.022 \times 10^{23}}\times \frac{195.081g Pt}{1 mol-Pt} = 1.59 g\ Pt$
