Three isotopes of element X have been discovered. Sixty percent exists at 42 amu, 30 percent weighs 45 amu and the last 10% weighs 48 amu. What is the atomic mass?

it is the most commonly accepted one

on passing the small ampere of electric current through the tube made of ar and hg of cfl generates uv rays which excites the fluorescent and thus emits the high radiation by consumption of just 5- 12 w in comparison to incandescent light which requires more power such as around 40 - 55 w to lighten.

moreover the life span of fluorescent or cfl is around 8000 h whereas the life span of incandescent is around 1200 h

hence, the building installed with incandescent lights bears more electricity bill.