1. The problem statement, all variables and given/known data 2. Relevant equations 3. The attempt at a solution I chose A as after googling, I learnt it was green. My question is: what is the green-blue precipitate. I am inclined to say [Cr(H2O)6]2+ as it's solution is blue, but ions don't precipitate. I tried searching and could find nothing. Could someone tell me what it is? Cheers!