Astudent weighed 0.3000 μg of sulfur in the lab. this is the same mass as

A student weighed 0.3000 μg of sulfur in the lab, this is equivalent to

As 1  μg= 10⁻⁶ g

    1 ng=10⁻⁹ g

So, 0.3000 μg =0.3×10⁻⁶ g

or

So, 0.3000 μg  is equal to  

So , 0.3000 μg  is equal to  

the answer for sodium is 0.186

the answer for rubidium is 0.251

i do not get it   at all