1. give us something that is light blue, not yellow.
QUESTION:
Which of the following observations is a definite sign that a chemical change has occurred?
Mixing a blue-colored liquid with a yellow-colored liquid, yields a green-colored mixture.
Mixing a blue-colored liquid with a colorless liquid yields a yellow-colored liquid
Neither
Both
Which of the following observations is a definite sign that a chemical change has occurred?
…Mixing a blue-colored liquid with a yellow-colored liquid, yields a green-colored mixture.
…Mixing a blue-colored liquid with a colorless liquid yields a yellow-colored liquid
…Neither
…or Both
PAUSE
An unusual color change is a definite sign that a chemical reaction has occurred.
Choice A is not an unusual color change. Our eyes perceive a mixing of the colors blue and yellow as green.
The observation given here does not necessarily mean that a chemical change has occurred.
CROSS OUT CHOICE A
Choice B is a definite sign that a chemical reaction has occurred. We would expect that a blue liquid mixed with a colorless liquid would
give us something that is light blue, not yellow.
Therefore, the correct answer is B.
HIGHLIGHT B
CLICK PAUSE END RECORDING

2. Video ID: © 2008, Project VALUE (Video Assessment Library for Undergraduate Education), Department of Physical Sciences Nicholls State University Author: Glenn V. Lo Narrator: Johuan Gasery Funded by Louisiana Board of Regents Contract No. LA-DL-SELECT-13-07/08