Understand the geometry of the flask and identify given dimensions.

Step 1: Understand the geometry of the flask and identify given dimensions.
The flask consists of a frustum of a cone at the bottom and a cylinder at the top.
For the frustum:

• Base diameter = $8.4 \text{ cm} \implies$ Base radius $R = \frac{8.4}{2} = 4.2 \text{ cm}$
• Top diameter = $3.5 \text{ cm} \implies$ Top radius $r = \frac{3.5}{2} = 1.75 \text{ cm}$
• Height of frustum $H_f = 8.4 \text{ cm}$ For the cylindrical part:
• Radius $r_c