Passage II
Seven 4 g mixtures of glycerol and agar were prepared, each having a different percent glycerol by mass. A plastic film was made from each mixture; all the films were rectangular and had the same dimensions.
Each film was clamped and stretched (see Figure 1) at 25°C until it broke.
Three properties of the film were determined:
• Tensile stress, the force applied per unit area of the film as the film broke
• Percent elongation, given by:
• Elastic modulus, a measure of the rigidity of the film
The results for all 7 films are shown in Figures 2 and 3.
Figures adapted from Eugene S. Stevens et al., "Polymer-Plastics Experiments for the Chemistry Curriculum." @2006by Division of Chemical Education, lnc., American Chemical Society.
11. Based on Figure 2, which of the following graphs best shows the percent elongation results for the films made from mixtures that were, respectively, 30%, 40%, and 50% glycerol by mass?
Your Answer is
Correct Answer is C
Explanation
Look at the solid line in figure 2, when the abscissa of the curve is 30, 40, 50, the ordinate is about 41, 25, 13