A simple experiment to demonstrate that NaOH is a stronger alkali than NH3

pH value test can be used to demonstrate that NaOH is a stronger alkali than NH3

Explanation:

pH value test can be used to demonstrate that NaOH is a stronger alkali than NH3. This is done by measuring the same volume of equal concentration of hydroxide and ammonia. A glass rod was dipped into 0.2 M of sodium hydroxide and 0.2 M of ammonia, each drop of solution was then placed on a pH paper matched with a color chart and the pH value was recorded.

The result showed that sodium hydroxide being a strong alkali would dissociate completely in aqueous solution thereby having a higher pH while ammonia would dissociate slightly/partially in aqueous solution thereby having a lower pH value

a corroding iron, if that's one of your choices

a is the correct answer