Pls help will give brainlist

Li buys supplies so he can make and sell key chains. he begins to make a profit only after he sells 4 key chains. what point on the graph makes the most sense in this situation?

Ibeg you to me 20. a reaction produces 4.93 l of oxygen, but was supposed to produce 1 mol of oxygen. what is the percent yield?

The following hormone had their receptors in the cell membrane except a-insulin b-tsh c-gh d- cortisol