The particles are quite tightly packed together but still have enough room to be able to move and flow, their bonds aren't as strong as a solids are
Yes it is polluting the river with everything the manufaturing plant gives off such as the chemicals released in the air
The most likely answer is the boiling point and freezing point of water. The Celsius scale starts at the freezing point of water (0°C) and than scaled so that 100°C fell on the boiling point of water.
I hope this helps. Let me know if anything is unclear.
Add an alkaline compound to raise the pH to 7.2.
