Is viscosity a vector or a scalar?

The flow of water in a river at the banks is slower than at the middle of the river. Explain.

Explain the velocity gradient and the coefficient of viscosity,and provide their units.

$A$ metal plate of area $10^{-2} \,m^2$ rests on a layer of castor oil, $2 \times 10^{-3} \,m$ thick, whose coefficient of viscosity is $1.55 \,Ns\, m^{-2}$. The approximate horizontal force required to move the plate with a uniform speed of $3 \times 10^{-2} \,ms^{-1}$ is (in $N$)

$A$ flat plate of area $0.1 \,m^2$ is placed on a flat surface and is separated from it by a film of oil $10^{-5} \,m$ thick whose coefficient of viscosity is $1.5 \,N \cdot s \cdot m^{-2}$. The force required to cause the plate to slide on the surface at a constant speed of $1 \,mm \cdot s^{-1}$ is ............ $N$.

The coefficient of viscosity for hot air is