Answer
$a_n=5\cdot (-1)^{n-1}$ and $a_{5}=5.$
Work Step by Step
We know that if $a_1$ is the first term and $r$ is the common ratio, then the nth term is: $a_n=a_1\cdot r^{n-1}.$
Hence here $a_n=5\cdot (-1)^{n-1}$ and $a_{5}=5\cdot (-1)^{5-1}=5.$