NextMockપરીક્ષાઓ શોધો, દા.ત. SSC CGL, UPPSC, Lekhpal
State PCS PYQPrelims 2025

BPSC – Combined Competitive Examination · પ્રશ્ન 132

Which compound is known as a glow-in-the-dark (night glowing) pigment?

  1. Europium-doped strontium aluminate
  2. Copper sulphide-doped zinc oxide
  3. Barium sulphate-doped copper carbonate
  4. Boron oxide-doped copper sulphate
જવાબ બતાવો અને સમજૂતી

જવાબ: (A) Europium-doped strontium aluminate

સમજૂતી

Europium (and dysprosium) doped strontium aluminate glows for hours after charging with light.

  • (A) સાચો

    Correct: SrAl₂O₄:Eu is the main long-afterglow phosphor.

  • (B) ખોટો

    Wrong: the older phosphor was copper-doped zinc sulphide, not this.

  • (C) ખોટો

    Wrong: not a luminous pigment.

  • (D) ખોટો

    Wrong: not a luminous pigment.