5. Which of the following numbers is not a square?
A $1^{6}$
B $2^{5}$
C $3^{4}$
D $4^{3}$
E $5^{2}$
5. B $1^{6}=\left(1^{3}\right)^{2}, 3^{4}=\left(3^{2}\right)^{2}, 4^{3}=64=8^{2}$ and $5^{2}$ are all squares. However, $2^{5}=32$ and is not a square.