The grids in the set above are not put in order, but there is a pattern.
The one on the right.
All the other diagrams have their blocks connected (horizontally, vertically or diagonally). This one has an isolated block.
I think the answer is:
The 5th count from left, due to there are only 1 or 2 separated white connected grid groups in each image but not the 5th which has 6 white connected grid groups.
The 5th from the left.
It is the only one that doesn't have a sibling block with +1 or -1 black squares.
Block 2 has one more black square than block 1
Block 3 has one more black square than block 2
Block 4 has one more black square than block 3
Block 7 has one more black square than block 6