Challenge: Practice More Methods from the NumPy Library

Write a program to achieve the following tasks:

1. Find indices of nonzero elements from [11, 22, 0, 0, 40, 50, 0].
2. Create a 5 x 5 identity matrix.
3. Create a 4 x 4 array with random values and find the minimum and maximum values.
4. Create an 8 x 8 array and fill it with a chess board pattern.