Which of the following was isolated and identified by Skoog and Miller?

If in a $\triangle ABC$,$\frac{1}{a+c} + \frac{1}{b+c} = \frac{3}{a+b+c}$,then $\angle C$ is equal to (in $^{\circ}$)

The rate of steady volume flow of water through a capillary tube of length $l$ and radius $r$,under a pressure difference of $p$ is $V$. This tube is connected with another tube of the same length but half the radius,in series. Then,the rate of steady volume flow through them is (The pressure difference across the combination is $p$.)

Let $f(x) = \int \frac{\sqrt{x}}{(1+x)^2} \, dx, x \geq 0$. Then $f(3) - f(1)$ is equal to

List-$I$ shows reactions involved in the metallurgy of $Pb$ (lead) and List-$II$ shows the names of the processes. Match List-$I$ with List-$II$ and select the correct code for your answer.

List-$I$	List-$II$
$(P). PbS + 2PbO \xrightarrow{\Delta} 3Pb + SO_2 \uparrow$	$(1).$ Smelting
$(Q). PbS + \frac{3}{2}O_2 \xrightarrow{\Delta} PbO + SO_2 \uparrow$	$(2).$ Self reduction
$(R). PbCO_3 \xrightarrow{\Delta} PbO + CO_2 \uparrow$	$(3).$ Calcination
$(S). PbO + C \xrightarrow{\Delta} Pb + CO \uparrow$	$(4).$ Roasting

An expression of energy density is given by $u = \frac{\alpha}{\beta} \sin \left(\frac{\alpha x}{kt}\right)$,where $\alpha$ and $\beta$ are constants,$x$ is displacement,$k$ is the Boltzmann constant,and $t$ is the temperature. The dimensions of $\beta$ will be $-$