<span>Use the sequence E (NaCl, Na2SO4, then Na2S). Silver is insoluble as a chloride, so it would be removed first, the others (Pb and Ni) are soluble as chlorides(Note; lead chloride is soluble as a hot solution but will ppt when cold), next, PbSO4 is insoluble but NiSO4 is soluble so use Na2SO4 to separate lead from nickel. Lastly, nickel sulfide is insoluble and can be separated and collected.
Hope I helped :)</span>
<span>A reducing agent loses electrons, so on the left side of the equation N in HNO2 has an oxidation number of +3 and on the right side in NO3^- it has an oxidation number of +5, so it has lost electrons. Thus, the reducing agent would be HNO2.</span>
The answer is D.
"a heterogeneous mixture and a suspension"
The metals one column to the right of the first have a charge of 2-. This is due to the element having an extra electron in comparison to the number of neutrons.
