I'm going to answer this by using rounded numbers for the atomic masses. You need only go back and put the numbers in from your periodic table. My answers will be close, but not what you should get.
Find the Molar Mass of MgCl2
Mg = 24 grams
2Cl = 2 * 35.5 = 71 grams
Total = 95 grams
Find the mols in 339 grams
1 mole = 95 grams
x mol = 339
Solve
339 = 95x Divide by 95
339/95 = x
x = 3.67 mols Answer
Choice 1
The Sun's radiation and solar wind cause the dust and gas around the comet (coma) to stretch the coma. The solar wind electromagnetically blows the ions in the coma away.
Answer:
Subtract the mass of the cylinder from the mass of the cylinder when it contains gasoline. This is the mass of the gasoline. Divide this figure by the volume, 100 ml, to get the density.