If 45.8 grams of mgo are dissolved in 205 grams of water, what is the concentration of the solution in percent by mass? 4.48% mgo 18.3% mgo 22.3% mgo 28.8% mgo

percent by mass = mass (MgO) / mass (solution)

mass of solution = 45.8 grams (MgO) + 205 grams (H2O) = 250. grams

mass (MgO) = 45.8 grams

percent by mass = 45.8 grams / 250. grams = 0.1832 = 18.32%

the density(ratio between mass and volume as m/v) decreases from top to bottom in periodic table group as the size increases and nuclear charge decreases. but in periods density increases from left to right as atom size decreases and nuclear charge increases.