Question

numbers of molecules present in 1 kg of oxygen

Answer 1

Hi......

Given mass of oxygen is 1Kg=1000g

Molar mass of oxygen 16u

No. of moles of oxygen =Given mass of oxygen/Molar mass of oxygen

=1000/16 moles

= 62.5 moles

Hence. No of molecules=no: of moles×Avogadro num =62.5×6.022×10^23 molecules =376.375×10^23 molecules

Answer 2

Hi there !!

Given mass of Oxygen = 1kg = 1000 grams 

Molar mass or Atomic mass of Oxygen = 16 u 

So,

No: of moles = Given mass / Molar mass
                     = 1000 / 16 = 62.5 moles

No: of molecules = No: of moles x Avogadro Number
                            = 62.5 x 6.022 x 10^23 
                           = 376.375 x 10^23 molecules