Product $(A)$ is

Consider the two following statements $A$ and $B$,and identify the correct choice given in the answers :
$(A)$ In photovoltaic cells the photoelectric current produced is not proportional to the intensity of incident light.
$(B)$ In gas-filled photoemissive cells,the velocity of photoelectrons depends on the wavelength of the incident radiation.

Choose the wrong statement:

$\int \frac{1+\cos 4 x}{\cot x-\tan x} d x$ is equal to

$8 \ mol$ of $AB_{3(g)}$ are introduced into a $1.0 \ dm^3$ vessel. If it dissociates as $2AB_{3(g)} \rightleftharpoons A_{2(g)} + 3B_{2(g)}$. At equilibrium,$2 \ mol$ of $A_2$ are found to be present. The equilibrium constant of this reaction is

If the angle between the pair of lines $x^2+2 \sqrt{2} x y+k y^2=0, k>0$ is $45^{\circ}$,then the area (in square units) of the triangle formed by the pair of bisectors of the angles between these lines and the line $x+2 y+1=0$ is