Question

A paisa coin weighs 0.75g and is square shaped with diagonal 17mm. Suppose, Al is electrically neutral,If the coin is made only of aluminium, find the magnitude of equal no. of +ve and -ve charges.

Answer 1

Atomic weight of aluminum is = 27 g/mol

Weight of paisa coin = 0.75

Number of moles of aluminum in the coin is, n = 0.75/27 = 0.028 mol

So, number of atoms in the coin is, N = nN_a

=> N = 0.028 × 6.022 × 10²³

Per atom there are 13 electrons and 13 protons. So, total number of electrons (-ve charges) and protons (+ve charges) on the paisa coin is = 13 × 0.028 × 6.022 × 10²³

= 2.19 × 10²³