Worst case time of insertion sort is O(n^2) when array is in decreasing order like 9, 8 , 7 ,6
Worst case time of merge sort is O(n*logn) . Time complexity of merge sort is always n*logn whether it is worst case , best case or average case
Worst case time of bubble sort is O(n*n) when array is in decreasing order
Worst case time of quick sort is O(n^2) . quick sort gives worst case time when it is in ascending order or descending order or when all elements of an array are same.