6. After completing an experiment, all chemical waste should be
A. left at your lab station for the next class.
B. disposed of according to your instructor's
directions.
C. dumped in the sink.
D. taken home.

B. disposed of according to your instructor's  directions.

Explanation:

After completing an experiment all chemical waste should be disposed of according to your instructor's directions.

Chemical wastes should be carefully handled in the laboratory so as not to carelessly release them into the environment. If not properly treated and they are discharged into the environment, they can lead to serious hazards and even pollution. Contamination is another very serious problem attributed to disposing chemical waste carelessly.

Instructor's guides should be followed to dispose chemical wastes.

considering the question as per the attachment

here we can see that the radon nuclide has 222 as the atomic mass number and 86 as the atomic number.

when it undergoes nuclear fission it gives polonium which has atomic mass number as 218 and atomic number will be 84 along with a helium nucleus which has 4 atomic mass number and 2 as its atomic number.

222 = 218 + 4 (atomic mass number)

86 = ? + 2; therefore ? = 86-2 = 84.

the atomic mass number of polonium will be 84.