11th Class Chemistry Some Basic Concepts of Chemistry

  • question_answer 41) Calculate the number of atoms present in: (i) 52 moles of He (ii) 52 amu He (iii) 52 g He (Atomic mass of Helium is 4 amu).  

    Answer:

    (i) Number of atoms s= Number of moles \[\times 6.023\times {{10}^{23}}\] \[=52\times 6.023\times {{10}^{23}}\] \[=3.13\times {{10}^{25}}\] (ii) 4 amu He has one atom. \[\therefore \] 52 amu He will have 13 atoms. (iii) Number of atoms \[=\frac{\text{mass}}{\text{Atomic}\,\text{mass}}\times 6.023\times {{10}^{23}}\] \[=\frac{52}{4}\times 6.023\times {{10}^{23}}\] \[=7.83\times {{10}^{24}}\]  


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