Answer
$2.15 \% \; Na_2SO_4$
Work Step by Step
Mass percentage = mass solute / mass solution * 100
Mass solute = 10.6 g Na$_2$SO$_4$
Mass solution = (10.6 g Na$_2$SO$_4$ + 483 g H2O)
$10.6\div(10.6+483)\times100=2.147$
Rounding to appropriate significant figures:
2.15% Na$_2$SO$_4$
