The question is incomplete, here is the complete question:
A chemist makes 600. mL of magnesium fluoride working solution by adding distilled water to 230. mL of a stock solution of 0.00154 mol/L magnesium fluoride in water. Calculate the concentration of the chemist's working solution. Round your answer to 3 significant digits.
<u>Answer:</u> The concentration of chemist's working solution is 
<u>Explanation:</u>
To calculate the molarity of the diluted solution (chemist's working solution), we use the equation:

where,
are the molarity and volume of the stock magnesium fluoride solution
are the molarity and volume of chemist's magnesium fluoride solution
We are given:

Putting values in above equation, we get:

Hence, the concentration of chemist's working solution is 
Hello!
The half-life is the time of half-disintegration, it is the time in which half of the atoms of an isotope disintegrate.
We have the following data:
mo (initial mass) = 43 g
m (final mass after time T) = ? (in g)
x (number of periods elapsed) = ?
P (Half-life) = 20 minutes
T (Elapsed time for sample reduction) = 80 minutes
Let's find the number of periods elapsed (x), let us see:






Now, let's find the final mass (m) of this isotope after the elapsed time, let's see:




I Hope this helps, greetings ... DexteR! =)
Answer:

Explanation:
Hello there!
In this case, since the formation of water from hydrogen and oxygen is:

Whereas we find a 2:2 mole ratio of hydrogen to water. In such a way, by using the Avogadro's number, the aforementioned mole ratio and the molar mass of water (18.02 g/mol), we obtain the following grams of water product:

Regards!
Answer:
51.54°C the final temperature of the calorimeter contents.
Explanation:


Molarity of HCl= 0.50 M
Volume of HCl= 150.0 mL = 0.150 L
Moles of HCl= n

Molarity of NaOH= 1.00 M
Volume of NaOH= 50.0 mL = 0.050 L
Moles of NaOH= n'

Since moles of NaOH are less than than moles of HCl. so energy release will be for neutralization of 0.050 moles of naOH by 0.050 moles of HCl.
n = 0.050


(1 kJ= 1000 J)
The energy change released during the reaction = 2800 J
Volume of solution = 150.0 mL + 50.0 mL = 200.0 mL
Density of the solution (water) = 1.00g/mL
Mass of the solution , m= 200 mL × 1.00 g/mL = 200 g
Now , calculate the final temperature by the solution from :

where,
q = heat gained = 2800 J
c = specific heat of solution = 
= final temperature = 
= initial temperature = 
Now put all the given values in the above formula, we get:


51.54°C the final temperature of the calorimeter contents.