Question

Which of the following has the highest number of
moles?
(1) 46 g of H2O (2) 83 g of O2
(3) 18 g of H2 (4) 112 g of N2

Answer 1

No. of moles = given mass /molar mass

In 46g H2O = 46/18 = 2.55 moles
In 83g O2 = 83/32 = 2.59 moles
In 18g H2 = 18/2 = 9 moles
In 112g N2 = 112/28 =4 moles
Hence 18g H2 have highest no. Of moles

Answer 2

answer : option (3) 18g of H2

explanation : we know, mole = given weight/molecular weight

(1) given weight = 46g

molecular weight of H2O= 18g/mol

so, mole = 46/18 = 2.55

(2) given weight = 83g

molecular weight of O2 = 32g/mol

so, mole = 83/32 = 2.59

(3)given weight = 18g

molecular weight of H2 = 2g/mol

so, mole = 18/2 = 9

(4)given weight = 112g

molecular weight of N2 = 28g/mol

so, mole = 112/28= 4

here it is clear that highest number of moles in option (3)

hence, answer is option (3) is correct