Alright, so the start point is the 2.6cm³. Next you use the density to find the amount in grams. The density can be written out as an identity which in this case would be 0.97gNa=1cm³Na. So you have this equation
2.6mL Na × [tex] \frac{0.97g Na}{1 mL} [/tex] ≈ 2.5g Na
Remember that 1cm³=1mL and that all answers must follow the rules of significant figures and rounding.
