D. Not all mixtures are heterogeneous
Answer: The given statement is true.
Explanation: If this reaction would have occurred, then this reaction would be considered as displacement reaction.
Displacement reactions are the reaction in which more reactive element displaces the less reactive element in a chemical reaction. This is based on the reactivity of elements.
Reactivity of elements is the tendency of the elements to gain or loose electrons. The reactivity decreases down the group in a periodic table.
In the given reaction, Iodine and chlorine are the elements of the same group in the periodic table and iodine lies below chlorine in the group. So, the reactivity of iodine is less than the reactivity of chlorine.
Hence, in the given reaction, iodine will not replace chlorine because it lies below in the periodic table.

Answer:
D
Explanation:
As bioindicators are the organism that indicate or monitor the health of the environment
Well the elements would be N, P, As, Sb, and Bi. Their electron configuration would be N= [He] 2s2 2p3, P= 1s2 2s2 2p6 3s2 3p3, As= [Ar] 3d10 4s2 4p3, Sb= Kr 4d10 5s2 5p3, and Bi= Xe 4f14 5d10 6s2 6p3.<span />