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JEE Main levelSingle correct optionDifficulty 2 of 3qa006

Assertion: The borax bead test is useful only for salts of some -block metals, because colourless metals give colourless beads. Reason: On heating, borax gives , which combines with metal oxides to form coloured metaborates.

  1. ABoth the assertion and the reason are true, and the reason explains the assertion
  2. BBoth the assertion and the reason are true, but the reason does not explain the assertion
  3. CThe assertion is true but the reason is false
  4. DThe assertion is false but the reason is true

Answer: A

Borax loses water and then . Acidic displaces the volatile oxide of the metal salt to give metaborates such as and , whose colours come from - transitions. Ions without such transitions give a colourless bead, so the assertion is a direct consequence of the reason.
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