Can the sides of a triangle have length 1,3 and 5

No.

Step-by-step explanation:

The two smallest sides must be greater than the biggest side when added up in order to form a complete triangle.

1+3 is 4, which is less than five, so the triangle wouldn't be connected.

Essentially, imagine a triangle where one line is too short to reach the other two, which is what was just explained--the smallest sides must add up to be greater than the biggest side in order to form a complete triangle.