<h3><u>Answer</u>;</h3>
≈ 4.95 g/L
<h3><u>Explanation;</u></h3>
The molar mass of KCl = 74.5 g/mole
Therefore; 0.140 moles will be equivalent to ;
= 0.140 moles × 74.5 g/mole
= 10.43 g
Concentration in g/L
= mass in g/volume in L
= 10.43/2.1
= 4.9667
<h3> <u> ≈ 4.95 g/L</u></h3>
The total mass is 10.57+6.96=17.53 g.
So, the percent by mass of magnesium is (10.57)/(17.53) * 100 = <u>60.3%</u>
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The percent by mass of oxygen is (6.96)/(17.53) * 100 = <u>39.7%</u>