How many bacteria are produced in four hours if a bacterium divides once in half an hour?

Which of the following statements is incorrect?

When a capacitor is connected in series to an $LR$ circuit,the alternating current flowing in the circuit

Suppose $A$ and $B$ are the points at which the line $x+y-\lambda=0$ meets the pair of straight lines $x^2+y^2-2x-4y+2=0$. If $\angle AOB=90^{\circ}$,then a value of $\lambda$ is

If $z=x+iy$ is a complex number satisfying $\left|z+\frac{i}{2}\right|^2=\left|z-\frac{i}{2}\right|^2$,then the locus of $z$ is

$ \int \frac{\sin 2x}{\sin^2 x + 2\cos^2 x} dx = $