30 !!! Around each electron that orbits an atom's nucleus .

A) a magnetic field

B) an electric current

C) a positive charge

D) a negative charge​

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