Asolution contains the ions ag+ , pb2+ and ni2+. dilute solutions of nacl, na2so4 and na2s are available to separate the positive ions from each other. in order to effect separation, the solutions must be added in which order?

 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 :)

Temperature and pressure

All the elements are arranged by melting points on the periodic table. in row they go from metals to gasses. in the row from sodium to argon, sodium is more reactive than the one on its right, magnesium.