a) When a block is resting on a flat surface, As long as it is at rest, it will exert a downward force on the surface which is a product of its mass and gravity. It will not move according to newtons first law of motion unless a force is applied. According to newton's third law of motion, there would be an opposite reaction that would balance this downward force. This is known as the normal force. The model of this scenario is shown below.
b) For the block with a 2 N force acting on it, the diagram is shown below.
For the first model, the object will remain at rest
For the second model, the applied force will cause the block to move towards the right since there is no frictional force to oppose the motion. The net force in the horizontal direction is 2N
