In which of the following is the renal portal system found?

The height of the cone of maximum volume inscribed in a sphere of radius $R$ is

Match the type of elasticity involved:

Process	Elasticity Type
$(i)$ Suspension fibre of galvanometer	$(a)$ Linear
$(ii)$ Bending of beam	$(b)$ Shear
$(iii)$ Cutting piece of paper	$(c)$ Bulk
$(iv)$ Mechanical waves in fluid	$(d)$ Shear

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

In order to shift a body of mass $m$ from a circular orbit of radius $3R$ to a higher radius $5R$ around the Earth,the work done is:

What is the probability of a couple having four sons?