The scientific method is "flexible". What does that mean? Why is that
important and necessary?

we can reach the same conclusions by applying different experimental and observational procedures

Explanation:

The scientific method is a process that can be summarized in the following steps: 1-to raise a question, 2-to make a hypothesis, 3-to obtain data from observations and/or experiments, and finally, 4-to obtain conclusions that enable to confirm (or reject) the hypothesis. The scientific method is flexible because it is not necessary to follow 'stringent' guidelines in order to reach the same conclusions. In consequence, the predictions derived from such results can be tested again to determine the veracity of the results.

n2(g) + 3h2-> 2nh3(g)   this is the balanced equation

note the mole ratio between n2, h2 and nh3.   it is 1 : 3 : 2   this will be important.

moles n2 present = 28.0 g n2 x 1 mole n2/28 g = 1 mole n2 present

moles h2 present = 25.0 g h2 x 1 mole h2/2 g = 12.5 moles h2 present

based on mole ratio, n2 is limiting in this situation because there is more than enough h2 but not enough n2.

moles nh3 that can be produced = 1 mole n2 x 2 moles nh3/mole n2 = 2 moles nh3 can be produced

grams of nh3 that can be produced = 2 moles nh3 x 17 g/mole = 34 grams of nh3 can be produced

note:   the key to this problem is recognizing that n2 is limiting, and therefore limits how much nh3 can be produced.

explanation: no but i do not usually comment