Aschool board is concerned that student test scores are being affected by
the fact that students do not get enough sleep at night. which of the
following is a testable hypothesis to use for finding whether or not this is
true?
a. children need at least two more hours of deep sleep at night than
adults need
b. children who eat breakfast and lunch achieve higher test scores
than children who skip either meal.
c. children who get more sleep at night eat healthier meals and
struggle less with obesity.
d. children who get a minimum of nine hours of sleep per night
achieve higher test scores than children who get fewer than nine
hours of sleep.

D. Children who get a minimum of nine hours of sleep per night

achieve higher test scores than children who get fewer than nine

hours of sleep.

answer: c. the experiment shows that the red substance experienced a chemical change.

explanation: chemical change is the change in which chemical composition of the substance changes. physical change is the change in which there is no change in chemical composition.

chemical changes are accompanied by following changes:

a) precipitate formation

b) energy is released or absorbed

c) formation of bubbles

d) change in color

as it is given that the red color has disappeared and there is production of gas, it means the red substance has undergone a chemical change.

e