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NEET-XII-Physics

29: Electric Field and Potential

with Solutions - page 3
Qstn# iv-9 Prvs-QstnNext-Qstn
  • #9
    Estimate the number of electrons in 100 g of water. How much is the total negative charge on these electrons?
    Ans : Molecular mass of water= 18 g
    Number of molecules in 18 g of H2O = Avogadro's number
    = 6.023 × 1023
    Number of electrons in 1 molecule of H2O = (2 × 1) + 8 = 10
    Number of electrons in 6.023 × 1023 molecules of H2O = 6.023 × 1024
    That is, number of electrons in 18 g of H2O = 6.023 × 1024
    So, number of electrons in 100 g of H2O = `` \frac{6.023\times {10}^{24}}{18}\times 100``
    = 3.34 × 1025
    ∴ Total charge = 3.34 × 1025 × 1.6 × 10-19
    = 5.34 × 106 C
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