Write the symbol or formula (including charge) for each of the following ions a ammonium ion b chromium ll ion c chromate ion d nitrate ion

i believe you are right for all except the 3rd ( look at sqdancefan his answer is much better)

answer; 4 electrons;

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.