A student measured the gram weight of a
metal object to be 71.2g. According to the
supplier the object weighs 70.9g. What is the
error in the student's measurement?

A
-0.3

B
+0.3

Astudent carefully transfers 30 g of water and 30 g of alcohol in a glass tube, forming two layers and filling the tube completely. after sealing the tube, the student mixes the solutions, and notices a bubble that forms in the tube. what is the mass of the contents in the glass tube after mixing?