For an investigation a student poured a blue solution of CuSO4 into a beaker. The student placed a shiny silver colored strip of zinc metal in the solution and observed the changes, The student inferred that a chemical reaction occurred. What evidence supports this inference?

It is the second answer; A dark solid formed on the zinc.

Explanation:

This is the correct answer because when a solid is formed it is called a precipitate, which is commonly known as a chemical reaction.

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.