Question

In borax bead test, the coloured ions give characteristic coloured beads due to the formation of:

• A. Metal borates
• B. Metal metaborates
• C. Metal phosphate
• D. Metal tetraborates

Answer 1

The correct option is B Metal metaborates

The borax bead test is a part of the qualitative inorganic analysis to test the presence of certain metals. The coated bead is heated initially in a lower reducing flame and then a higher oxidizing flame. Mostly $\text{the characteristic}$ $\text{colours arises due to the formation of metal metaborates}$salts of chromium, copper or nickel.

$N{a}_2{B}_4{O}_7+CuS{O}_4\to 2NaB{O}_2+\underset{\text{Copper metaborate.}\left(blue\right)}{Cu(B{O}_2{)}_2}+S{O}_3$

Option B is the correct answer.