Which of the following is true about the coefficient of static friction $(\mu_s)$ and the coefficient of kinetic friction $(\mu_k)$?

$A$ horizontal force of $10 \, N$ is necessary to just hold a block stationary against a wall. The coefficient of friction between the block and the wall is $0.2$. The weight of the block is ........ $N$.

$A$ $20\, kg$ block is initially at rest on a rough horizontal surface. $A$ horizontal force of $75\, N$ is required to set the block in motion. After it is in motion,a horizontal force of $60\, N$ is required to keep the block moving with constant speed. The coefficient of static friction is

The blocks $A$ and $B$ are arranged as shown in the figure. The pulley is frictionless. The mass of $A$ is $10 \, kg$. The coefficient of friction of $A$ with the horizontal surface is $0.20$. The minimum mass of $B$ to start the motion will be...... $kg$.

$A$ force $\vec{F}=\hat{i}+4 \hat{j} \, N$ acts on the block of mass $1 \, kg$ shown in the figure. The coefficient of friction between the block and the surface is $\mu = 0.3$. The force of friction acting on the block is (Take $g = 10 \, m/s^2$)

As shown in the figure,a force $F$ is applied on a block of mass $\sqrt{3} \ kg$ placed on a rough horizontal surface. The maximum value of $F$ for the block not to move is (Coefficient of static friction between the block and the surface is $\mu = \frac{1}{2 \sqrt{3}}$ and acceleration due to gravity $g = 10 \ m \ s^{-2}$). (in $N$)