Question about Newtons third law

[yaseen shah]

in Newtons third law of motion every action has equal and opposite reaction so my question is that when block hits another block the blocks exert equal force on another so why they move they had to stop immediately.

 

[sophiecentaur]

On impact, each block will deform slightly. During the actual time taken for the impact (a finite time- not immediate) the blocks will be compressed / twisted / bent and there will be forces acting against each block (the Newton 3 pair).