12 g of commercial zn is made to react with
excess dil H₂So4.
The total volume of H2 gas
literated was found to be 4.2 l at 500 mm
of Hg pressure and
pressure and 279 . Determine percentage
purity of zn

a

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.