Which of the following pairs have same number of atoms? *
 


16g of O₂ and 4g of H₂
16g of O₂ and 44g of CO₂
28g of N₂ and 32g of O₂
6g of C and 23g of Na

Dear Student

The third pair, i.e. 28g N₂ and 32g O₂ have same number of atoms. 

Molar mass of N = 14 g and molar mass of O = 16 g
Molar mass of N₂ = 2*14 = 28 gram and Molar mass of O₂ = 2*16 = 32 grams

Now 1 mole of a compound has 6.022*10²³ molecules.
Hence, both 28 grams N₂ and 32 grams O₂ have 6.022*10²³ molecules or 12.044*10²³ atoms (1 mole has 2 atoms each).

Regards