Answer : The volume of 1 M NaOH solution required are, 400 mL
Explanation :
To calculate the volume of base, we use the equation given by neutralization reaction:

where,
are the n-factor, molarity and volume of acid which is

are the n-factor, molarity and volume of base which is NaOH.
We are given:

Putting values in above equation, we get:


Therefore, the volume of 1 M NaOH solution required are, 400 mL