Molar mass Na2SO4 = <span>142.04 g/mol
142.04 g -------------- 6.02x10</span>²³ atoms
?? g ------------------ 7.4x10²³ atoms
142.04 x ( 7.4x10²³) / 6.02x10²³
=> 174.60 g
Bronsted-Lowry acid is your answer
The rails expand during the heat of a summer day
The drawing above is acting as a B) a screw.