What is the mass of 29.6 mol of the element nickel (Ni)?

Well, $1$ $m o l$ of nickel metal has a mass of $58.69 \cdot g$. So....approx. $1800 \cdot g$
You have $29.6 \cdot m o l$, so...............
$29.6 \cdot \cancel{m o l} \times 58.69 \cdot g \cdot \cancel{m o {l}^{-} 1}$ $=$ ??g