$A$ neutron makes a head-on elastic collision with a stationary deuteron. The fractional energy loss of the neutron in the collision is

Identify the incorrect statements from the following.
$I$. Tin in $+2$ state acts as reducing agent while lead in $+4$ state acts as strong oxidising agent.
$II$. Silicon exists as $[SiF_6]^{2-}$ form,but $[SiCl_6]^{2-}$ does not.
$III$. The hybridisation of carbon in fullerene is $sp^3$.
$IV$. Among $Ge, Sn$ and $Pb$,the lowest melting point is for $Sn$.

If $l_1 = \lim_{x \rightarrow 2^{+}} (x + [x])$,$l_2 = \lim_{x \rightarrow 2^{-}} (2x - [x])$ and $l_3 = \lim_{x \rightarrow \pi / 2} \frac{\cos x}{x - \pi / 2}$,then:

$A$ particle is released from a height $H$. At a certain height,its kinetic energy is half of its potential energy with reference to the surface of the earth. The height and speed of the particle at that instant are respectively:

$A$ spherical portion has been removed from a solid sphere having a charge distributed uniformly in its volume as shown. The electric field inside the emptied space is

Silica is added to roasted copper ore during extraction in order to remove