We want to find how much charge is on the electrons in a nickel coin. follow this method. a nickel coin has a mass of about 5 g. find the number of atoms in a nickel coin. each mole (6.02 × 1023 atoms) has a mass of about 58 g. answer in units of atoms.

The mass of a nickel coin is 5 g.
1 mol of Ni weighs 58 g. 1 mol contains 6.022 x 10²³ atoms of Ni.
therefore in 58 g  there are 6.022 x 10²³ atoms of Ni
then in 5 g the number of Ni atoms are - 6.022 x 10²³ /58 x 5 = 5.2 x 10²² Ni atoms
Therefore number of Ni atoms are 5.2 x 10²² atoms in a nickel coin

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30litre of li2o is 1.0002mole approximately 1 mole