Identify the type of precipitate formed in the following reaction: $(NH_4)_2SO_4 + Ba(OH)_2 \longrightarrow BaSO_4 \downarrow + 2NH_3 \uparrow$

$A$ chemistry student trying to detect the metallic ion in a salt,makes a paste on a clean platinum wire loop of the salt with concentrated $HCl$. When he takes a small amount of this paste and keeps it in a non-luminous Bunsen flame,the colour of the flame changes to grassy green. He should,therefore,conclude that the metal is

Identify the technique used to know the binding nature of nanomaterials.

Which of the following salts is used in the bead test for the qualitative analysis of inorganic substances?

Identify the last step in wet chemical synthesis of nanomaterial.

Given below are two statements:
Statement $I$: Colourless cupric metaborate is reduced to cuprous metaborate in a luminous flame.
Statement $II$: Cuprous metaborate is obtained by heating boric anhydride and copper sulphate in a non-luminous flame.
In the light of the above statements,choose the most appropriate answer from the options given below.