You already have one of the two answer(s) selected... (C). The other answer is E, because (27/9) = 3, then you add x. As letter C, the answer is 3x.
What Do you mean 6 passwords?
5 times 1/10 is 5/10 or 1/2 of a kg. This equals 0.5 kg. You can do 3 experiments (use up until 4.5 kg)
