From the figure, it can be observed that
Height (h1) of each conical part = 2 cm
Height (h2) of cylindrical part = 12 − 2 × Height of conical part = 12 − 2 ×2 = 8 cm
Radius (r) of cylindrical part = Radius of conical part = 3/2 cm
Volume of air present in the model = Volume of cylinder + 2 × Volume of cones