The density of copper is `9xx10^3 kg m^(-3)` and its atomic mass is 63.5 u. Each copper atom provides one free electron. Estimate the number of free electrons per cubic metre in copper.

Options

A. `10^(19)`
B. `10^(23)`
C. `10^(25)`
D. `10^(29)`

Answer

D

Explanation

`rho_(Cu) = 9 xx 10^(3) kg//m^(3), m_(Cu^(-)) = 63.5 g`
No. of electron per unit volume
`=N_(A)/M rho =(6.02 xx 10^(23))/(63.5 xx 10^(-3)) xx 9 xx 10^(3)`
`=0.85 xx 10^(29)//m^(3)`
Approx = `10^(29)//m^(3)`