Final answer:
The tax per liter is $8.
Step-by-step explanation:
To find the tax per liter, we need to calculate the difference between the price paid by consumers and the price received by producers. Given that consumers pay $14 per liter and producers receive $6 per liter, the tax per liter can be calculated as:
Tax per liter = Price paid by consumers - Price received by producers = $14 - $6 = $8
So, the tax per liter is $8.