To solve this problem we need to have an idea about molarity. The concentration can be expressed as:
Molarity = moles/ L
1dm^3 = 1L
According to the ration given, there are 15 g or N atoms per 100 grams of Fertilizer. So the percent mass would be 15% N. Next, we have get the amount of nitrogen present in 14 grams of fertilizer.
14 x (15/100) = 2.1 grams N
There are 2.1 grams of nitrogen atoms in 14 grams of fertilizer. Now we convert 2.1 grams of N to moles of N.
2.1 grams N x ( 1mole N / 14 grams N) = 0.15 moles N
Finally, we can get the concentration in Molarity.
Molarity = 0.15moles/5 dm^3
Molarity = 0.15 moles/dm^3 or moles/L