(a) The quantity √13 is irrational and therefore is non-terminating when expressed as a decimal. Dividing by a rational number does not change the situation.
(b) Here we need to look more closely at whether the two square roots combine: √325/√52=√(325/52)=√(25/4)=5/2. So the square root does rationalise and (b) becomes 5/1250=1/250=0.004, which is terminating.