Which of the following aqueous solutions

Question

should form a precipitate with aqueous
Fe(NO3)3?
1. KCl
2. KNO3
3. KOH
4. K2SO4

Answer 1

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

see rule 5, note rule 3.

You need to make flash cards of these rules, and memorize them.

Answer 2

it's not 2

Answer 3

the answer is 3. KOH