$A$ rod $P$ of length $1 \ m$ is hinged at one end $A$ and there is a ring attached to the other end. Another long rod $Q$ is hinged at $B$ and it passes through the ring. The rod $P$ is rotated about an axis which is perpendicular to the plane in which both the rods are present and the variation between the angles $\theta$ and $\phi$ are plotted as shown. The distance between the hinges $A$ and $B$ is ....... $m$.

The correct order of acidic strength of the major products formed in the given reactions is:
$A.$ $PhNH_2$ $\xrightarrow[\substack{\text{(2) } CuCN \\ \text{(3) } H_3O^{+} / \Delta}]{\text{(1) } NaNO_2 + HCl \left( < 5^{\circ} C \right)} [A]$
$B.$ $CH_3CH_2CHO \xrightarrow[\Delta]{\left[ Ag \left( NH_3\right)_2\right]^{+}, OH^{-}} [B]$
$C.$ $CH_4 + O_2 \xrightarrow[\text{(ii) } Na_2Cr_2O_7 / H^{+}]{\text{(i) } Mo_2O_3} [C]$
$D.$ $PhCH_2MgBr + CO_2 \xrightarrow[H_3O^{+}]{\text{Dry ether}} [D]$
Choose the correct answer from the options given below:

What is the first step in the Southern Blotting technique?

$A$ ball is dropped from a height of $20 \ m$ above the surface of water in a lake. The refractive index of water is $4/3$. $A$ fish inside the lake, in the line of fall of the ball, is looking at the ball. At an instant, when the ball is $12.8 \ m$ above the water surface, the fish sees the speed of the ball as ........ $m/s$ $[g = 10 \ m/s^2.]$

Which of the following statements is not correct when a junction diode is in forward bias?

Which of the metabolites is common to respiration-mediated breakdown of fats,carbohydrates,and proteins?