Answer:
The answer to your question is: letter B
Explanation:
Reaction
Cr2O3(s) + 3CCl4(l) ⇒ 2CrCl3(s) + 3COCl2(g)
From the information given and the reaction, we can conclude that:
Green solid = Cr2O3 (s) "s" means solid
Colorless liquid = CCl4 (l) "l" means liquid and is the other reactant
Purple solid = CrCl3(s) CrCl3 is purple and "s" solid
Then, as a green specks remains it means that the excess reactant is Cr2O3, so, CCl4 is the limiting reactant.
Just the number 2 to get the cofficients
Violet, indigo, blue, green, yellow, orange, red
If he was 30.8% too low, it means that he was at 69.2% of the boiling point needed. So 50o C is 69.2% of total.
In order to know what 100% is, you can divide the number by it's percentage and then multiply it by a hundred.
So: 50/30.8=1.623
1.623*100=162.3
So the correct boiling point of the liquid he was working with in the lab is 162.3 oC