Hints:

$$ Liquid level in the tank is your controlled variable,

$$ You have air$-$to$-$close pneumatic control valve on the inlet stream pipe, i$.$e$.$ Fi is manipulated variable,

$$ We do not have any disturbance in this problem,

$$ Linearize the differential equation,

$$ Write transfer function of process, valve and sensor transmitter couple,

$$ Find numerical values of gain and time constant of the process, valve and sensor$-$transmitter models,

$$ Draw closed loop block diagram,

$$ For part $($a$)$ you can use any one of the method that is presented in the lecture,

$$ Do not forget units of parameter values