The balanced equation below represents the reaction between magnesium metal and hydrochloric acid to produce aqueous magnesium chloride and hydrogen gas.

mg(s) + 2hcl(aq) ==> mgcl2(aq) + h2(g)

a piece of mg(s) has a volume of 0.0640 cubic centimeters. this piece of mg(s) reacts completely with hcl(aq) to produce h2(g). the h2(g) produced has a volume of 112 milliliters and a pressure of 1.00 atmosphere at 298 k.

65 the volume of the piece of mg(s) is expressed to what number of significant figures?