How do static friction oppose motion ? Value of coefficient of friction depend on which factors ?

Someone is using a scissors to cut a wire of circular cross section and negligible weight. The wire slides in the direction away from the hinge until the angle between the scissors blades becomes $2 \alpha$. The friction coefficient between the blades and the wire, is :-

A body of mass $2 \,kg$ is kept by pressing to a vertical wall by a force of $100\, N$. The coefficient of friction between wall and body is $0.3.$ Then the frictional force is equal to ........ $N$

A chain of length $L$ rests on a rough table. If $\mu $ be the coefficient of friction, the maximum friction of the chain that can hang over the table will be

The limiting friction between two bodies in contact is independent of

In the figure shown, a block of weight $10 \,N$ resting on a horizontal surface. The coefficient of static friction between the block and the surface ${\mu _s} = 0.4$. A force of $3.5\, N$ will keep the block in uniform motion, once it has been set in motion. A horizontal force of $3 \,N$ is applied to the block, then the block will