What quality do units represent in a value

100mg magnesium reacts with 20ml of 1.0m hcl

Tin has ten stable isotopes. the heaviest, 124sn, makes up 5.80% of naturally occuring tin atoms. how many atoms of 124sn are present in 82.0 g of naturally occurring tin? what is the total mass of the 124sn atoms in this sample?

Analyze how limestone is weathered and identify the features that are formed as a result of this dissolution