Approximately how many grams does 3 x 10²³ atoms of Cu weigh? What mass of sodium contains the same number of atoms as 27 grams of Aluminum?

Which of the following statements are true?

A Hydrogen atom is too small to be seen by the naked eye
A Hydrogen atom can be weighed on a grocer's scale
All Hydrogen atoms have he same mass
All Hydrogen atoms behave chemically in the same way

Which of the following statements concerning the carbon-12 atom is true

It is the basis for the atomic mass scale
It weighs 12.0 g
It is more abundant in nature than carbon -13
It has an atomic number of 12