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ChemistryJEE Main 28 Jan 2026, Shift 2·Q17·MCQ·Easy–moderate

p-Block (13–14) · Borax bead test

Consider the following reactions.

NaX2BX4OX7→Δ2 X+Y\ce{Na2B4O7}\xrightarrow{\Delta}\ce{2X + Y}

CuSOX4+Y→Non-Luminous flameZ+SOX3\ce{CuSO4 + Y}\xrightarrow{\text{Non-Luminous flame}}\ce{Z + SO3}

2 Z+2 X+Carbon→Luminous flame2 Q+NaX2BX4OX7+CO\ce{2Z + 2X + Carbon}\xrightarrow{\text{Luminous flame}}\ce{2Q + Na2B4O7 + CO}

The oxidation states of Cu in Z and Q, respectively are :

  1. (1)+2+2 and +2+2
  2. (2)+2+2 and +1+1
  3. (3)+1+1 and +2+2
  4. (4)+1+1 and +1+1

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See the full 28 Jan 2026, Shift 2 paper