Body elements and trace fossils I believe
Here, we have to get the number of atoms present in the 100 plane of the FCC crystal lattice.
There will be 2 atoms in 100 plane of FCC crystal lattice.
In the face centered crystal (FCC) lattice there are atoms at each corner of the cube and each are shared by 4 another atoms. And an atom is present at the face of the crystal.
For the 100 plane of the Miller indices the intercepts are a, ∞, ∞ or 2a, ∞, ∞.
Thus, for the 4 atoms of the corner at the cube shared by 4 other atoms will contribute, 4 ×
= 1 and the un-shared atoms at the face will contribute another 1, which make the total atom 1 + 1 = 2.
You can solve this problem through dimensional analysis.
First, find the molar mass of NaHCO3.
Na = 22.99 g
H = 1.008 g
C = 12.01 g
O (3) = 16 (3) g
Now, add them all together, you end with with the molar mass of NaHCO3.
22.99 + 1.008 + 12.01 + 16(3) = 84.008 g NaHCO3. This number means that for every mole of NaHCO3, there is 84.008 g NaHCO3. In simpler terms, 1 mole NaHCO3 = 84.008 g NaHCO3.
After finding the molar mass of sodium bicarbonate, now you can use dimensional analysis to solve for the number of moles present in 200. g of sodium bicarbonate.

Cross out the repeating units which are g NaHCO3, and the remaining unit is mole NaHCO3
200. * 1 = 200
200/ 84.008 = 2.38
Notice how there are only 3 sig figs in the answer. This is because the given problem only gave three sig figs.
Your final answer is 2.38 mol NaHCO3.
Answer:
O H C
Moles in 100g 3.33 6.65 3.33
Ratio 1.00 2.00 1.00
Possible empirical formula = 
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:
.