Question

Which of the following do not respond to borax beat test?

• A. Nickel salts
• B. Copper salts
• C. Cobalt salts
• D. Aluminium salts

Answer 1

Answer: (D)

Aluminium salts

Borax bead test is used for detection of transition metals.
Borax when heated with salts of transition metals, yields salt of certain colours.
When borax is heated with copper sulphate, a blue salt of copper metaborate is formed.

• $N{a}_2{B}_4{O}_7\to 2NaB{O}_2+B_2{O}_3$

• $CuS{O}_4\to CuO+S{O}_3$

• $CuO+B_2{O}_3\to Cu(B{O}_2{)}_2$

Those compounds containing colourless ions doesn't show borax bead test. E.g. Zinc, Aluminium, Calcium, Barium.

Hence option (D) is correct.