Calculate the mass (in g) of 2.1 x 1020 atoms of Os.

here's the procedure to find it friend

Explanation:

How do you find the mass in grams of an atom?

In order to determine the mass of one atom of an element, you must determine its molar mass, which is its atomic weight on the periodic table in g/mol, and you need to know the relationship between moles and the number of atoms: 1 mol of atoms = 6.022×1023 atoms . Then divide the molar mass by 6.022×1023 atoms/mol .

the answer is:  

line graphs show patterns in data with variables that change over time; whereas, circle graphs show data as parts out of a whole (such as out of 100%).

i think it's letter a.