Answer
$^{51}$V
Work Step by Step
To determine which of the two naturally occurring isotopes of vanadium is most abundant, we look at the average atomic mass of vanadium, which is 50.942 amu from our periodic table. Because 50.942 amu is closer to 51 than to 50, that means that $^{51}$V is more abundant than $^{50}$V.
