Question

3 litre and 5 litre vessel and i had to measure exactly 4 litres using them).

Answer 1

Take the 3 litre vessel pour twice
In the poured water using 5 litre take 5 litre from it the reminding will be 1 litre
From the 5 litre use 3 litre vessel take 3 litre and pour in the 1 litre
You will get 4 litre