In the group the reactivity of metals increases? give example

As sodium and potassium both are alkali metals that belong to Group IA of the periodic table. They have one valence electron in their valence shell. As we move from top to bottom, the reactivity of metallic elements of Group IA increases.

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.