Whats the minimum amount of times you should run an experiment

Can someone me with 3 and 4 plz. this is for masteries test.

How many moles of bromine are needed to produce 3.23 moles of potassium bromide

Which of the following warnings would an agricultural chemist tell a farmer who wants to recycle his or her own ammonia? recycling ammonia is a difficult process that sometimes takes weeks. recycling ammonia requires a degree in biochemistry or a related field. recycling ammonia can be harmful because it is highly flammable and toxic. recycling ammonia costs too much money considering the price of the necessary chemicals.