Answer
0.0182 mm
Work Step by Step
Volume=$\frac{\text{mass}}{\text{density}}=\frac{2.568\,g}{2.70\,g/cm^{3}}=0.95111\,cm^{3}$
Volume=area of the square$\times$thickness
$\implies 0.95111\,cm^{3}=(22.86\,cm)^{2}\times\text{thickness}$
Or thickness of the foil=$\frac{0.95111\,cm^{3}}{(22.86\,cm)^{2}}=0.00182\,cm$
$=0.0182\,mm$ (As 1 cm=10 mm)
