Good laboratory technique demands clean glassware because the most carefully executed piece of work may give an erroneous result if dirty glassware is used. In all instances, glassware must be physically and chemically clean and in many cases, it must be bacteriologic-ally clean or sterile.
Your answer is 3! Hope you get a good grade :)♥
I think it is 11% I read it on a article on msn.
