The number of atoms present in one mole of an element is equal to Avogadro number. Which of the following elements contains the greatest number of atoms ?

Options

A. 4g He
B. 46 g Na
C. 0.40 g Ca
D. 12 g He

Answer

D

Explanation

For comparing number of atoms, first we calculate the moles as all are monoatomic and hence moles `xx N_(A)` = number of atoms .
Moles of 4g He `= (4)/(4) =1` mol
46g Na ` = (46)/(23) = 2` mol
0.40 g Ca ` = (0.40)/(40) = 0.1` mol
12 g He `= (12)/(4) = 3` mol
Hence, 12g He contains greatest number of atoms as it possesses maximum number of moles.