Assume that sodium atoms are spheres of radius 0.2 nm and that they are lined up side by side. How many miles, in length, is the line of atoms present in a 1.15 mg sample of sodium? `(N_(A) = 6 xx 10^(23))`

Options

A. `1.2 xx 10^(10)`
B. `1.2 xx 10^(8)`
C. `7.5 xx 10^(8)`
D. `7.5 xx 10^(6)`

Answer

D

Explanation

Number of molecules of sodium `= (1.15 xx 10^(-3))/(23) xx 6 xx 10^(23)`
Length in metre `= 0.2 xx 5 xx 6 xx 10^(18) xx 10^(-9) xx 2`
Length in miles `= 0.000621 xx "Length in metres"`