Define phosphorescence

Fluoroscence differs from phosphorescence in being

Assertion: Emission of light as result of exposure of P to air in night is called phosphorescence. Reason: Phosphorus burns in O_(2) to give P_(2)O_(5) and conversion of chemical energy into light energy producing cold light and the phenomenon is called chemiluminiscence.

An allotrope of phosphorous, exhibits a phenomenon of phosphorescence, produces compound 'A' which on reacition with O_(2) gives 'B'. The number of oxygen atoms bonds to each central atom in 'A' and 'B' are 'X' and 'Y' respectively. When 'A' is heated to 210^(@)C it decomposes to an oxide 'D' and another allotrope of phosphorus 'C'. X and Y are respectively

An allotrope of phosphorous, exhibits a phenomenon of phosphorescence, produces compound 'A' which on reacition with O_(2) gives 'B'. The number of oxygen atoms bonds to each central atom in 'A' and 'B' are 'X' and 'Y' respectively. When 'A' is heated to 210^(@)C it decomposes to an oxide 'D' and another allotrope of phosphorus 'C'. The 'C" and 'D' are

Phosphorescence occus in