Consider the following statements:

(A) Chromium (III) chemical species is more toxic than Chromium (VI)

(B) Dimethylmercury chemical species is more toxic than methylmercury ion

(C) Arsenic (III) is more toxic than Arsenic (V)

Which of the above statements is/are correct?

Correct option is C

Introduction:

• Toxicology is the study of the adverse effects of chemical substances on living organisms.
• In speciation (the specific chemical form of an element) is often more important than the total concentration, as different forms have vastly different solubility, bioavailability, and toxicity.

Information Booster:​

• Dimethylmercury is more toxic than methylmercury ion:
• While all organic mercury is dangerous, Dimethylmercury $$(CH_3)_2Hg$$​ is one of the most potent neurotoxins known.
• It is a volatile liquid that can penetrate latex gloves and skin with ease. Monomethylmercury $$(CH_3Hg^+)$$​ is the form that commonly bioaccumulates in fish, but dimethylmercury is significantly more lethal in acute doses.
• Arsenic (III) is more toxic than Arsenic (V): 
• Arsenite [As(III)] is roughly 10 to 60 times more toxic than Arsenate [As(V)].
• As(III) binds to sulfhydryl groups in proteins and enzymes, disrupting their function, while As(V) acts as a phosphate analogue, interfering with oxidative phosphorylation (ATP production).

Additional knowledge:

• Chromium (III) is more toxic than Chromium (VI):
• Cr(VI) (Hexavalent Chromium) is a known human carcinogen and is significantly more toxic than Cr(III) (Trivalent Chromium).
• Cr(VI) can easily cross cell membranes via sulfate transport systems, whereas Cr(III) is an essential micronutrient in small quantities for insulin metabolism.