Identify $A$ and $B$ in the following reaction:
$A \xrightarrow[\Delta]{aq. NaOH} C_2H_5OH \xleftarrow{AgOH} B$

Which of the following is mismatched?

$A$ vessel contains oil (density $= 0.8 \, g/cm^3$) over mercury (density $= 13.6 \, g/cm^3$). $A$ homogeneous sphere floats with half of its volume immersed in mercury and the other half in oil. The density of the material of the sphere in $g/cm^3$ is

The value of $\int_{0}^{1} \tan ^{-1}\left(\frac{2 x-1}{1+x-x^{2}}\right) d x$ is

The depletion layer in the $p-n$ junction is caused by

Which of the following is not a Pteridophyte?