The impulse is given by the area under the graph of F vs t, on a given interval.
Notice that the area under the given graph has the shape of a triangle. Its base has a "length" of 10 seconds, while its height is 5 Newtons. The area of a triangle is half the product of its base times its height. Then, the impulse on the object is:
![\begin{gathered} I=(1)/(2)(10s)(5N) \\ =25N\cdot s \\ =25\operatorname{kg}\cdot(m)/(s) \end{gathered}]()