A spherical ball of radius 7cm contains 56% iron. If density is `1.4g"/"cm^(3)`, number of moles of Fe present approximately is

Options

A. 10
B. 15
C. 20
D. 25

Answer

C

Explanation

Volume of spherical ball `= (4)/(3) pi r ^(3) = (4)/(3) xx (22)/(7) xx (7) ^(3)`
Mass `= V xx d = (4)/(3) xx (22)/(7) xx (7) ^(3) xx 1. 4 g`
Fe `(56%) = (4)/(3) xx (22)/(7) xx (7) ^(3) xx 1. 4 xx (56)/(100) g = 1126.4,` number of moles of Fe = 20