Answer:
1.41 L
Step-by-step explanation:
Initially the concentration of NaOH was 9.0M (say M1) finally the concentration becomes 3.0M (say M2)
intial volume (say V1) is to be calculated when the final volume (say V2) is 4.25L
we have,
M1V1=M2V2
or V1=(M2V2)/M1= 3.0×4.25/9.0= 1.41L
Hence 1.41 L of 9.0M solution is required to prepare 4.25L of 3.0M NaOH solution