UPSC 2017 CDS I GK Paper

The number of atoms in 46 g of sodium-23 (N = Avogadro constant) is 2N, molar mass of Na = 23 gm/mol,
Number of moles of Na in 46 gm=

46

23

=2mol
Number of atoms in 46 gm of Na is = 2 × Avogadro number=2×6.03×1023
=12.06×1023 atom = 2N
Hence, number of atoms in 46g of sodium-23 (N = Avogadro constant) = 2N