Please help if you're good at science/ biology.. I NEED A 100!! (7th grade) Explanation plss! (I'll mark brainiest if right!)

What is the name for a substance formed in a chemical reaction

In what for do plants utilize nitrogen? why do they need nitrogen?

20 points and brainlist 1. london has suffered from terrible air pollution for at least seven centuries. why is the city so prone to its famous “london fog? ” what did london do to get rid of its air pollution? 2. why does air pollution cause problems in developing nations more than in developed ones?