What is difference between primary and standard solution?

A standard solution is solution that is a containing a precisely known concentration of an an element. Primary  it's typically a reagent which can ve weighed very easily, and which is so pure that the weight of it is truly representative of the number of molecules that it contained 

We can’t you if you only tell us that you have to show us what the answers are

The mass has escaped into a gas which you can not see so the law stays true.