Answer:
[0,4,0,2,0]
Explanation:
You need to iterate through the list and check if the index is even by comparing the rest of its division by 2 with 0. This can be achieved using the following algorithm (written in Python, so it can easily be translated to other languages)
mylist = [3,4,1,2,89]
for i in range(0, len(mylist)): #For each index of the list
if i%2==0: #If the rest of the division of i by 2 is 0, which means it is even
mylist[i]=0 #Assigns zero to current index