Aluminum is 26.982 grams per mole, so 26.982/19.9 will give you the moles 1.3558794
Answer:
.
Explanation:
Based on the electron configuration of this ion, count the number of electrons in this ion in total:
.
Each electron has a charge of 
.
Atoms are neutral and have 
charge. However, when an atom gains one extra electron, it becomes an ion with a charge of . Likewise, when that ion gains another electron, the charge on this ion would become 
.
The ion in this question has a charge of . In other words, this ion is formed after its corresponding atom gains two extra electrons. This ion has 
electrons in total. Therefore, the atom would have initially contained 
electrons. The atomic number of this atom would be 
.
Refer to a modern copy of the periodic table. The element with an atomic number of is sulphur with atomic symbol 
. To denote the ion, place the charge written backwards ("
" for a charge of ) as the superscript of the atomic symbol:
.
Answer:
100 J of energy are needed to heat the copper from 20∘C to 80∘C .
Answer: b
Explanation:
By adding heat you are adding more energy
