Answer:
We could do two 1:50 dilutions and one 1:4 dilutions.
Explanation:
Hi there!
A solution that is 1000 ug/ ml (or 1000 mg / l) is 1000 ppm.
Knowing that 1 ppm = 1000 ppb, 100 ppb is 0.1 ppm.
Then, we have to dilute the stock solution (1000 ppm / 0.1 ppm) 10000 times.
We could do two 1:50 dilutions and one 1:4 dilutions (50 · 50 · 4 = 10000). Since the first dilution is 1:50, you will use the smallest quantity of the stock solution (if we use the 10.00 ml flask):
First step (1:50 dilution):
Take 0.2 ml of the stock solution using the third dispenser (20 - 200 ul), and pour it in the 10.00 ml flask. Fill with water to the mark (concentration : 1000 ppm / 50 = 20 ppm).
Step 2 (1:50 dilution):
Take 0.2 ml of the solution made in step 1 and pour it in another 10.00 ml flask. Fill with water to the mark. Concentration 20 ppm/ 50 = 0.4 ppm)
Step 3 (1:4 dilution):
Take 2.5 ml of the solution made in step 3 (using the first dispenser 1 - 5 ml) and pour it in a 10.00 ml flask. Fill with water to the mark. Concentration 0.4 ppm / 4 = 0.1 ppm = 100 ppb.
<span>when the number of moles Ca = mass of Ca / molar mass of Ca.
and we can get the molar mass of Ca, it is = 40 g/mol
and we have already the mass of Ca (given) = 9.8 g
so, by substitution: the moles Ca = 9.8 g / 40 g/mol
= 0.245 moles</span>
Answer: The ionic formula of compound is 
and the name is cobalt phosphide.
Explanation:
For formation of a neutral ionic compound, the charges on cation and anion must be balanced. The cation is formed by loss of electrons by metals and anions are formed by gain of electrons by non metals.
Here element Co is having an oxidation state of +3 called as 
cation and phosphprous forms 
anion with oxidation state of -3. Thus they combine and their oxidation states are exchanged and written in simplest whole number ratios to give neutral
The nomenclature of ionic compounds is given by:
1. Positive is written first followed by the oxidation state of metal in roman numerals in square brackets.
2. The negative ion is written next and a suffix is added at the end of the negative ion. The suffix written is '-ide'.
Thus the name of is cobalt phosphide.
Answer: Barium is +2, Fluorine is -1
Explanation:
The charge of barium is +2, and the charge of fluorine is -1. You can determine this from the periodic table groups.
The formula for barium fluoride is thus BaF2.
N = (PV)/RT
(T = 88.78 + 273 = 361.78K)
(R = 22.4/273 = 0.082)
= (5.49 x 22.03)/(0.082 x 361.78) = ?
Put it into the calculator. It's hard to do that on a mobile phone.
