Ypu guys please help me if u are good with science

Astudent poured a solution of bromothymol blue indicator into three test tubes. then he placed an aquatic plant in two of the test tubes, as shown below. he placed a stopper on each test tube and placed them all in the dark for 24 hours. bromothymol blue turns from blue to yellow in the presence of co2

How can we use spectral lines of light coming from the superclusters to identify which is receding from earth at the slowest rate.

Which of these definitions have been paired with the correct type of cell?