Ncert Solutions Chemistry Class 12th

S > O > Se > Te   

Leaching of Al₂O₃ with alkali;

$\begin{array}{l}A{l}_2{O}_3\left(s\right)+2NaOH\left(aq\right)+3H_{2}O\left(l\right)\to 2Na\left[Al{\left(OH\right)}_4\right]\left(aq\right)\\ X\end{array}$            

$\begin{array}{l}2Na\left[Al{\left(OH\right)}_4\right]\left(aq\right)+2C{O}_2\left(g\right)\to A{l}_2{O}_3.x{H}_{2}O\left(s\right)+2NaHC{O}_3\left(aq\right)\\ XYZ\end{array}$

Both (A) and (B) are correct but R is not correct explanation of A. In both $T\mathcal{l}{l}_{3}andCs{l}_3$ oxidation state of metal is +1, also both have similar lattice structure.   $T\mathcal{l}=4f^{14}5d^{10}6s^{2}6p^1$

It does not contains 2^nd most abundant element by weight in earth crust because that is Si Calgon ->Na₂ [Na₄ (PO₃)₆] $\underset{}{\overset{Watersoluble}{\to }}2N{a}^{+}{\left[N{a}_4{\left(P{O}_3\right)}_6\right]}^{2-}$

$\underset{}{\overset{C{a}^{2+}}{\to }}2N{a}^{+}{\left[N{a}_{2}Ca{\left(P{O}_3\right)}_6\right]}^{2-}$

Ceric ammonium nitrate is used to test alcohol while CHCl₃/alc. KOH is used to test 1° amine

$FeC{l}_3\underset{}{\overset{hydrolysis}{\to }}Fe{\left(OH\right)}_3\downarrow \underset{Adsorption}{\overset{F{e}^{3+}}{\to }}Fe{\left(OH\right)}_3|F{e}^{3+}\left(colloidalparticle\right)$                                                                                               

Caprolactum is monomer of nylon-6

Isoprene is polymer of natural rubber

2 – chloro-1,3-butadiene or chloroprene is the polymer of neoprene which is a synthetic rubber

Acrylonitrite is one of the monomer of Buna-N

Acrylonitrile