Questions

Here Oil is the most viscous liquid.

The liquid with the most intermolecular force is high viscous. viscosity is how smoothly a liquid flows and how hardly the liquid flows it is highly viscous.

With demand paging, a page is brought into memory only when a location on that page is actually referenced during execution. With pre-paging, pages other than the one demanded by a page fault are brought in. The selection of such pages is done based on common access patterns, especially for secondary memory devices.

Barometer is instrument which is used to measure to pressure. A slow downfall of reading suggests a low pressure area is passing in a nearby region, it may rains. If the reading is going down very fast then its an indication of storm (within 5-6 hours).

Time taken for switching from one process to other is pure over head. Because the system does no useful work while switching. So one of the solutions is to go for threading when ever possible.