Which of the following is least viscous? a. Plastic c. Metal ...

[j.rubin]

Which of the following is least viscous?
 
  a. Plastic c. Metal
  b. Gelatin (e.g., Jell-O) d. Glass

Question 2

A small-diameter glass tube is placed upright in a container of mercury. The meniscus at the top of the column of mercury is convex. This demonstrates that the:
 
  a. cohesive forces of mercury are weak.
  b. cohesive forces of mercury are strong.
  c. adhesive forces within the mercury are strong.
  d. adhesive forces between the mercury and the glass are strong.

[alexisweber49]

Answer to Question 1

ANS: B
Plastic, metal, and glass have cohesive forces between the molecules that are strong enough to prevent any movement under normal circumstances. Jell-O's viscosity will increase with low temperatures and decrease as temperature rises.

Answer to Question 2

ANS: B
The cohesive forces within the mercury are stronger than the adhesive forces between the mer-cury and the glass. If the cohesive forces within the mercury were weaker than the adhesive forces, the meniscus would be concave. See Box 1-5.