This is an incomplete question, here is a complete question.
Calculate the volume in milliliters of a 1.29 mol/L iron(II) bromide solution that contains 275 mmol of iron(II) bromide . Round your answer to significant 3 digits.
Answer : The volume of iron(II) bromide solution is, 
Explanation : Given,
Concentration of iron(II) bromide = 1.29 mo/L
Moles of iron(II) bromide = 275 mmol = 0.275 mol
conversion used : 1 mmol = 0.001 mol
Now we have to calculate the volume of iron(II) bromide.

Now put all the given values in this formula, we get:

Thus, the volume of iron(II) bromide solution is, 
10 electrons will occupy the five orbitals in the atoms d sub shell like this. Each electron fills one by one in each orbital. So first 1 electron will fill the first orbital, then the second will move on to the next and so on. So for example…if there were 7 electrons, the first two sub shells would be filled, and the other three would have one electron each