Answer:
One distinguishing feature between physical and chemical changes is that a physical change can be reverse or turn back to its original form, but chemical change cannot be return to its form because the material change.
Explanation:
The plant will grow towards the light source.
Yasir wanted to study the relationship between sleep and room color. So he has done all the background study required on the topic and arrived at a hypothesis that people fall asleep more rapidly in a room painted in blue color than in a room painted yellow. Yasir inquired several people which color they like better -yellow or blue- and used their feedback to decide whether his hypothesis was correct. There was no experiment conducted to observe the effect of a room color on sleep and the variables to be tested in the experiment were not properly identified.
Therefore, the correct answer would be,
An experiment that directly tests the hypothesis
Variables to be tested by an experiment
I believe it is spontaneous generation
