[填空题]
What is the total charge of all the ele68/u;o5,fihhvj kwi e w-)ozfctrons in a 15-kg bar of aluminwdpg .5gvzghv,9q 3j9qziw(5 um? $ \times10^{8 }\,C$What is the net charge of the bar? C (Aluminum has 13 electrons per atom and an atomic mass of 27 u.)
