A stock solution contains 5 g per 100 ml of sucrose. How many ml of this stock solution would you use to prepare 1 litre of sucrose solution at a concentration of 0.25 g per litre?
1 Answer
5 mL
Explanation:
It's a dilution problem since it starts with a concentrated stock solution and a lower concentration solution is prepared from it.
First of all, we'll need to do is calculate the 2 concentrations that are given:
We can do that using 2 ways:

#Molarity = "mol" / "volume in L"#
Using this formula will require additional calculation, converting from grams to mol using molar mass of sucrose. 
#%(m/v)=("g of solute")/("mL of solution")xx 100%#
I'll proceed using this concentration. Take note on the unit required for mass (g) and volume (mL).
We also know from the question, that the final volume of solution
Since we need to find out the volume of stock solution used (