Given below are two statements:

Statement I: Nano scale metallic and bimetallic particles can efficiently remove common water pollutants such as Poly Chloro Benzenes (PCR), Organo chlorine pesticides and halogenated organic solvents.

Statement II: Nano scale metallic and bimetallic particles cannot reduce heavy metals such as nickel, arsenic, mercury etc.

In the light of the above statements, choose the most appropriate answer from the options given below.

The correct option is: Statement I is correct but Statement II is incorrect.

Let us analyze each statement step-by-step to understand why this option is correct.

Step 1: Evaluation of Statement I
Statement I states that nano-scale metallic and bimetallic particles can efficiently remove common water pollutants such as Polychlorinated Biphenyls (PCBs) / Poly Chlorinated Benzenes, organochlorine pesticides, and halogenated organic solvents.
Nano-scale metallic particles (especially zero-valent iron, commonly known as nZVI) and bimetallic nanoparticles (such as Fe/Pd, Fe/Ni, etc.) possess an extremely high specific surface area and high reactivity. These nanoparticles act as powerful reducing agents. They facilitate the dechlorination and degradation of persistent halogenated organic compounds (like halogenated solvents, PCBs, and organochlorine pesticides) by transferring electrons, effectively reducing them into less toxic or non-toxic forms. Therefore, Statement I is chemically correct.

Step 2: Evaluation of Statement II
Statement II states that nano-scale metallic and bimetallic particles cannot reduce heavy metals such as nickel, arsenic, mercury, etc.
This statement is incorrect. Highly reactive nano-scale metallic particles (like nZVI) possess a low reduction potential and are highly effective in removing heavy metal ions from water. The removal mechanisms include reduction (where heavy metals with higher reduction potential than iron, such as Cr(VI), Hg(II), Ni(II), and Pb(II), are reduced to lower, less soluble, or less toxic oxidation states), adsorption, and co-precipitation. For instance, arsenic is strongly adsorbed onto the iron oxides formed during the reaction, while metals like mercury and nickel can undergo reduction and immobilization on the nanoparticle surfaces. Since nano-scale particles can reduce and remove these heavy metals, Statement II is false.

Conclusion:
Since Statement I is correct and Statement II is incorrect, the chosen option is the most appropriate answer.