A - 7g N 2

B - 2g H 2

C - 16g NO 2

D - 16g O 2

 

Answer

B - 2g H 2

 

Explanation: 

Number of moles = Given mass of substance / Molecular mass of substance 

                        n  = m / M

                 

7g N 2 → 7 / 28 = 0.25 moles of molecules

2g H 2 → 2 / 2 = 1 mole of molecules

16g NO 2 → 16 / 46 = 0.347 moles of molecules

16g O 2 → 16 / 32 = 0.5 moles of molecules

 

Thus 2g H 2 has the most number of molecules.

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Maninder Singh

CA Maninder Singh is a Chartered Accountant for the past 14 years and a teacher from the past 18 years. He teaches Science, Economics, Accounting and English at Teachoo