Which of the following is self-adjusting in nature?

Static friction between two surfaces:

$A$ force of $19.6\, N$ when applied parallel to the surface just moves a body of mass $10\, kg$ kept on a horizontal surface. If a $5\, kg$ mass is kept on the first mass,the force applied parallel to the surface to just move the combined body is........ $N.$

In the figure shown,a horizontal force $F_1$ is applied on a block,but the block does not slide. Then,as the magnitude of the vertical force $F_2$ is increased from zero,the block begins to slide. Which of the following statements is correct?

Given below are two statements:
$Statement$ $(I)$: The limiting force of static friction depends on the area of contact and is independent of materials.
$Statement$ $(II)$: The limiting force of kinetic friction is independent of the area of contact and depends on materials.
In the light of the above statements,choose the most appropriate answer from the options given below:

Which of the following forces does not depend on the velocity: the frictional force between the contact surfaces of two solids or the viscous force?