If you could explain what “merkels” are, the question would be more clear.
I think the correct answer would be none, because the wall will block the radiation. Alpha particles can only penetrate a very thin sheet of paper and is totally blocked by the concrete. As these particles move through the air, it loses energy from the collisions with air molecules making it less penetrating.<span />
H2O
This equation is a double displacement reaction, and it forms H2CO3, which is very unstable and separates into H2O and CO2.
The atom that is oxidized : Cr
The oxidizing agent : H₃PO₄
<h3>Further explanation</h3>
Reaction
2 H₃PO₄ (aq) + 2Cr(s) → 2 CrPO₄ (aq) + 3H₂(g)
Atoms undergoing a reduction reaction (decrease in oxidation number) and an oxidation reaction (increase in oxidation number)
H⁺(in H₃PO₄) =+1
H₂=0
Cr = 0
Cr³⁺(in CrPO₄ )
the oxidizing agent.⇒which undergoes a reduction reaction and oxidizes another compound/element : H₃PO₄
