Pre-Assignment

1. Why is the surface of a liquid destabilised relative to the bulk?
2. Does a molecule in the body of a ‘polar liquid’ experience forces of attraction uniformly in all directions?
3. Which one is easier – to move an object through the surface or to move it when it is completely submersed and why?
4. Why does the surface tension decrease with increase in temperature?

Post-Assignment

1. How were the observations of the experiment with distilled water different from that with hard water?
2. Why should one not drop the detergent solution near the floating needle?
3. Why do the powder flakes move towards the edges of the beaker on addition of drops of detergent solution?
4. Why do soap bubbles last for long times whereas bubbles in pure water often burst and disappear quickly?
5. Why does hard water require more detergents or soaps to form leather?