Question

Which of the following contains minimum number of molecules?
(i) 46 g of ethyl alcohol
(ii) 54 g of nitrogen pentaoxide

Answer 1

(i) Molar mass of ethyl alcohol (C₂H₅OH) is 46 g/mol
So, 46 g of ethyl alcohol will have 6.023  × 10²³ molecules,
(ii) Molar mass of nitrogen pentaoxide (N₂O₅) is 108 g/mol
So, 54 g of N₂O₅ will contain 1/ 2 mole
i.e., 6.023  × 10²³  × (1/2) molecules.
= 3.0115  × 10²³ molecules
Hence, 54 g of nitrogen pentaoxide will have minimum number of molecules.