The state and output equations for a control system are:

$$ \begin{aligned} & \dot{x}=\left[\begin{array}{cc} -4 & -1.5 \\ 4 & 0 \end{array}\right] x+\left[\begin{array}{l} 2 \\ 0 \end{array}\right] u \\ & y=\left[\begin{array}{ll} 1.5 & 0.625 \end{array}\right] x \end{aligned} $$

Which of the following expressions correctly represents the transfer function $\frac{Y(s)}{U(s)}$ of the system with zero initial conditions?

Consider the unity negative feedback control system shown in the Figure. The value of gain $K(>0)$ at which the given system will remain marginally stable is $\_\_\_\_$ . (Answer in integer)

In the circuit shown in the Figure, $A$ and $B$ are logic inputs and $Y$ is the logic output. Which of the following logic operations is realized by the circuit?

A binary ripple counter is designed to count $(0)_{10}$ to $(64)_{10}$. Which of the following is/are the number of flip-flops required to design the counter?