In the reaction Mg (s) + 2HCl (aq) → H2 (g) + MgCl2 (aq) , what is the species oxidized, species reduced, oxidizing agent, reducing agent?

And what is the Oxidation half-reaction and Reduction half-reaction?

What are the spectator ions in 2h+ + so42- + ca2+ + 2r → caso4 + 2h+ + 21?

The content of manganese (mn) in steel was determined spectrophotometrically and with the use of the standard addition method. an unknown sample of mn from a digested steel sample gave an absorbance of 0.185 when analyzed spectrophotometrically. when 5.00 ml of solution containing 95.5 ppm mn was added to 50.0 ml of the unknown steel solution (digested sample), the absorbance was 0.248. calculate the concentration, in parts-per-million (ppm), of mn in the digested steel sample solution.

The appropriate concentration for an iodine sanitizer is