Answers

2016-02-28T18:25:50+05:30
A watch glass is a circular concave piece of glass used in chemistry as a surface to evaporate a liquid, to hold solids while being weighed, as a cover for a beaker, and for heating a small amount of substance. The latter use is generally applied to prevent dust or other particles entering the beaker; the watch glass does not completely seal the beaker, so gas exchanges still occur.
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