NCERT Question 9 (b) - Chapter 3 Class 9 - Atoms And Molecules

Last updated at Dec. 16, 2024 by

What is the mass of:

(b) 0.5 mole of water molecules?

 

Answer

We know that,

Number of moles of a substance = Given mass of the substance / Molar mass of the substance

 

Therefore,

Mass of the substance = Number of moles x Molar mass of the substance

                              

 

(b) 0.5 mole of water molecules

Given mass of H 2 O = m = ?

Molar Mass of H 2 O = M = 18g

Number of moles = n = 0.5 = 5/10 = 1/2

We know that,

Mass of the substance = Number of moles x Molar of the substance

 m = n x M

     = (1/2) x 18

     =  18/2

     = 9g

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