Which has more number of atoms, 100 grams of sodium or 100 grams of iron? (Given: Atomic masses of Na = 23u, Fe = 56u)

In order to solve this problem, we should convert 100 grams of sodium into moles of sodium, and also 100 grams of iron into moles iron. The element having more moles will have more atoms. Please note that since the atomic mass of sodium is 23u, the molar mass of sodium will be 23 g/mol. Similarly, since the atomic mass of iron is 56u, the molar mass of iron will be 56 g/mol. We will now calculate the moles of sodium atoms (Na) and iron atoms (Fe), one by one.

(i) Moles of sodium = Mass of sodium/Molar mass of sodium


= 100/23


= 4.34


(ii) Moles of iron = Mass of iron/Molar mass of iron


= 100/56


= 1.78


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