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

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.

Which ion gives a violet-coloured bead in the borax bead test?

The compound called microcosmic salt is

Which of the following solid salt on heating with solid $K_2Cr_2O_7$ and conc. $H_2SO_4$ evolves orange-red vapours that turn an aqueous $NaOH$ solution yellow?

The salt used for performing the 'bead' test in qualitative inorganic analysis is