Which of the following metals releases hydrogen gas upon reaction with cold and dilute $HNO_3$?

Match the items in Column-$I$ with those in Column-$II$:

Column-$I$	Column-$II$
$A$. Tapetum	$i$. Degenerate during development
$B$. Intine	$ii$. Resistant organic materials
$C$. Vegetative cell	$iii$. Pollen tube
$D$. Sporopollenin	$iv$. Provide nourishment to pollen grains

If the water falls from a dam into a turbine wheel $19.6\, m$ below,then the velocity of water at the turbine is ............. $m/s$ $(g = 9.8\,m/s^2)$.

The point $P$ is equidistant from $A(1, 3)$,$B(-3, 5)$,and $C(5, -1)$. Then $PA =$

Two identical metal plates show the photoelectric effect when light of wavelength ${\lambda _A}$ falls on plate $A$ and ${\lambda _B}$ falls on plate $B$,where ${\lambda _A} = 2{\lambda _B}$. The maximum kinetic energy is:

The formula of ferrocene is