Question

Materials used to make rain proof coats and tents are water proof due to:

• A. Surface tension
• B. Viscosity
• C. Specific gravity
• D. Elasticity

Hint:

Think about why water forms round beads on a waxed or coated surface instead of spreading out.

Answer 1

The Correct Option is A

Step 1: Note the coating.
Rain proof fabric is treated with a wax like or water repelling coating before use, which changes how water behaves on its surface.
Step 2: Recall what surface tension does.
Surface tension makes the water molecules pull together into small rounded drops instead of spreading out flat, because a sphere gives the smallest possible surface area for a given volume of liquid.
Step 3: Apply it to the coated fabric.
On the coated cloth, each drop keeps a small contact area with the fibres due to surface tension, so it cannot be pulled deep into the tiny gaps between threads by capillary action.
Step 4: See the outcome.
The rounded drop simply sits on top of the fabric and rolls off under its own weight instead of soaking in.
Final Answer: A) Surface tension.