Answer:
22mm²
Explanation:
There are 6 sides of a "cell": 3 different types of sides with different dimensions that are multiplied twice because there is a front and back side with the same dimensions.
Front and back side = 2 × 5mm × 1mm
= 10mm²
Left and right side = 2 × 1mm × 1mm
= 2mm²
Up and down side = 2 × 5mm × 1mm
= 10mm²
Total surface area = 10mm² + 2mm² + 10mm²
= 22mm²
