20 ml of NaOH is neutralised by 10 ml of HNO3. How much NaOH will be required to neutralise 15 ml of HNO3?

30 ml NaOH will be required to neutralise 15 ml of HNO3. This is calculated using the concept of neutralization and proportionality. 20 ml of NaOH neutralizes 10 ml of HNO3; so the ratio is NaOH/HNO3 = 20/10 = 2. Now, for 15 ml of HNO3, NaOH = 2 x 15 = 30 ml.