#given
w=100#gms
A=(w*6.022*10**23)/107.868
print "the number of atoms in the given amount of silver is" ,A
from math import pi
# Initialisation of Variables
r=1.5*10**-7;#Radius of a particle in cm
rho=7.8;#Density of iron magnetic nano- particle in cm**3
#CALCULATIONS
v=(4./3.)*pi*(r)**3;#Volume of each Iron magnetic nano -particle in cm**3
m=rho*v;#Mass of each iron nano-particle in g
print "Volume of each Iron magnetic nano -particle in cm**3:",v
print "Mass of each iron nano-particle in g:",m
from math import exp
# Initialisation of Variables
Es=1.8;#Electro negativity of Silicon from fig.2-8
Eo=3.5;#Electro negativity of Oxygen from fig.2-8
#CALCULATION
F=exp(-0.25*(Eo-Es)**2);#Fraction covalent of SiO2
print "Fraction covalent of SiO2 :",round(F,3)