Surface Chemistry — Chemistry STD 12 Science — Question

$(A)$ Hydrolysis of Marshall's acid gives $H_2SO_4$ and $H_2O_2$ as final product

$(B)$ In $SCNSiH_3$ structure around $N$ is bent

$(C)$ Basic unit for silicates is $SiO_4^{-4}$

$(D)$$N{H_4}Cl + NaOH \to N{H_3} \uparrow $

$Y$  in the above reaction is