Answer: 4 ml
In this case, the injectable form of enalapril is available as 1.25 mg in 1ml solution.
The patient should be given 5 mg in total for 6 hours.
So, in 1.25 mg of Enalapril is available in 1ml.
Therefore, in 5mg of Enalapril will make (1/1.25) X 5 = 4ml