Bài 2: Các ion A2+, B+ , X-
, Y2- đều có cấu hình electron của khí hiếm Ar (Z =18). Viết cấu hình e của
nguyên tử ứng với các ion trên. Xác định các nguyên tố A, B, X, Y.

in theory, limestone is composed principally of the compound calcium carbonate - caco3, but in reality this compound is deposited in conditions involving a number of other compounds as impurities so it ends up being a mixture of many compounds.

hope this : -)

tony (lordcaos066)

i think its 100

i hope this !

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.