Ohm's Law states V = IR
So,
I = V/R
The answer is B. 10/5=2 amps
Well the trivial answer is zero, since there is indeed a "zero vector". Assuming you aren't allowed to use the zero vector you would need at least two. They would be antiparallel and of equal magnitude. (That is be pointing in opposite directions and have the same length)
It is currently organised by the increasing atomic # based on the actual nuclear charge of the elements