The following list contains some common polyatomic ions. Using the charge on these ions and the idea of valence, predict the formulas for the compound formed from the following:

nitrate NO3-1 phosphate PO4-3
sulfate SO4-2 acetate C2H3O2-1
ammonium NH4+1 chromate CrO4-2
carbonate CO3-2 dichromate Cr2O7-2
permanganate MnO4-1 sulfite SO3-2
ammonium and sulfite

A. (NH 4) 2SO 3
B. NH 4SO 4
C. (NH 4) 2SO 4
D. NH 4SO 3

answer: - 3.) the oxidation state of nitrogen in no changes from +2 to 0, and the oxidation state of carbon in co changes from +2 to +4 as the reaction proceeds.

solution: - as per the rules, oxidation number of oxygen in its compounds is -2. the sum of oxidation numbers of all the elements of a molecule or compound is zero.

also, the oxidation number in elemental form is zero.

in no, the oxidation number of o is -2 so the oxidation number of n is +2 so that the sum is zero.

similarly, the oxidation number of c in co is +2 and o is -2.

on product side the oxidation number of n is 0 as it is in the elemental form() .

oxidation number of c in carbon dioxide is +4 as there are two oxygen in it and we know that each oxygen is -2.

so, oxidation number of n is changing from +2 to 0 and the oxidation number of c is changing from +2 to +4.

since nitrogen is reduced and hence no is acting as an oxidizing agent. carbon is oxidized and so co is acting as a reducing agent.

so, the right choice is number 3.)the oxidation state of nitrogen in no changes from +2 to 0, and the oxidation state of carbon in co changes from +2 to +4 as the reaction proceeds.

c, liquids evaporate, creating a gas