Why must safe practices and methods be used in laboratory activities?

So the people doing it will be safe and so they will know what to do

Safe practices and methods must be used in laboratories because dangerous chemical are often used and could sometimes potentially put one's life in danger. For example, goggles are used to prevent chemicals that may cause blindness from getting into someone's eyes and lab-coats are used to protect clothing. Another practice is to keep your hair tied up if it is long because it could get caught on fire!

Well, a and b together would be negative. b alone would also be negative.

Why you put last one a? i think is b.