Option 1: N/2 - This option suggests that the number of atoms in 46 g of sodium-23 would be half of Avogadro`s constant (N). This is incorrect because Avogadro`s constant represents the number of atoms in one mole of a substance, not half a mole. Therefore, this option is incorrect.

Option 2: N - This option suggests that the number of atoms in 46 g of sodium-23 would be equal to Avogadro`s constant (N). This is incorrect because Avogadro`s constant represents the number of atoms in one mole of a substance. However, 46 g of sodium-23 is not equal to one mole, so this option is incorrect.

Option 3: 2N - This option suggests that the number of atoms in 46 g of sodium-23 would be twice Avogadro`s constant (N). This is the correct answer because 46 g of sodium-23 is equivalent to one mole, which contains Avogadro`s constant number of atoms. As a result, the number of atoms in 46 g of sodium-23 is 2N.

Option 4: 23N - This option suggests that the number of atoms in 46 g of sodium-23