Among the choices, the polyatomic ion is only the third choice, NH4+ where it is composed of nitrogen one atom of nitrogen and 4 atoms of hydrogen. Choice 2 is a monoatomic atom being composed only of calcium. Then, the first and fourth choices are not ions because they are not charged.
The balanced equation for the above reaction is as follows;
Mg + 2HCl ---> MgCl₂ + H₂
stoichiometry of HCl to MgCl₂ is 2:1
we have been told that Mg is in excess therefore HCl is the limiting reactant
number of HCl moles reacted - 0.100 mol/L x 0.0256 L = 0.00256 mol
according to molar ratio, number of MgCl₂ moles formed - 0.00256/2
Therefore number of MgCl₂ moles formed - 0.00128 mol
mass of MgCl formed - 0.00128 mol x 95.20 g/mol = 0.122 g
The answer would actually be false. I just took the test.
1, 2, and 3
hope it helps next time upload with picture
