Answer:
No, the farmer is not able to move the mule.
Explanation:
Mass =100 kg
Force=F=800 N
The coefficient between the mule and the ground=

Static friction force,f=
Normal force=N=mg
Static friction force,f=
Using 
F<f
Static friction force is greater than applied force.
Therefore , the farmer is not able to move the mule.
The impact of the material
type with which the slope is made affects the acceleration. Acceleration will
be higher and smoother if the material of the slope surface is smoother as
opposed to a texture which is not smooth. Smoother surface allows more acceleration
because it will have less friction and resistance. Otherwise the friction will
slow the object down for example a grassy ground will have more friction than a
well maintained marble floor.
Third
every action has an opposite and equal reaction
Neutrons have a zero charge but consist of mass.