How do these react? Some may have no reaction.

Question

a. aqueous chromium(III) nitrate plus magnesium metal

b. aqueous lithium sulfate plus aqueous barium chloride

c. solid lead metal plus aqueous potassium chloride

d. aqueous lithium fluoride with aqueous ammonium phosphate

Answer 1

You need two tables to answer these. You should have a good feel for these two tables and know solubility rules and know the placement of metals in the activity series.
http://www.files.chem.vt.edu/RVGS/ACT/notes/solubility_rules.html

http://www.files.chem.vt.edu/RVGS/ACT/notes/activity_series.html

For example.
a)This is a single replacement type reaction. Any metal in the table will displace an ION of a metal below it in the activity series. Mg is above Cr; therefore,
Cr(NO3)3 + Mg ==> Mg(NO3)2 + Cr(s)
You balance it.

Li2SO4 + BaCl2 ==> BaSO4 + 2KCl. This proceeds because BaSO4 is insoluble.

I'll leave the last two for you. If the metal (in reactions like a), if the metal is not ABOVE the ion, you write no reaction. For reaction in which a solid or a gas is formed, you write the reaction. Otherwise you write no reaction.