Impending relative motion is opposed by which type of friction?

$A$ force $F = mg$ is acting on a block of mass $m$ as shown in the figure. The pushing of the block along the surface is possible if:

As shown in the figure, a block of mass $10 \ kg$ lying on a horizontal surface is pulled by a force $F$ acting at an angle $30^{\circ}$ with the horizontal. For $\mu_{s} = 0.25$, the block will just start to move for the value of $F$: [Given $g = 10 \ ms^{-2}$] (in $N$)

Static friction between two surfaces:

Find the minimum value of mass $m$ that should be placed on the $20 \, kg$ block so that the system remains at rest. (Given coefficient of friction $\mu = 0.25$) (in $, kg$)

$A$ block of mass $2 \, kg$ is kept on the floor. The coefficient of static friction is $0.4$. If a force $F$ of $2.5 \, N$ is applied on the block as shown in the figure,the frictional force between the block and the floor will be ........ $N$.