91Ó°ÊÓ

The mass of a single atom in a chemical element is known as its atomic mass.

The size of an atom is determined by its atomic mass.

a)

Let us solve the given problem.

The formula for the relationship between proton radius, nucleus radius, and atomic mass is:

\(\begin{aligned}{}r = {r_0}{A^{\frac{1}{3}}}\\A = {\left( {\frac{r}{{{r_0}}}} \right)^3}\end{aligned}\)

Where \({r_0} = \) radius of proton, \(r = \)radius of nucleus and \(A = \)atomic mass

Now plug in the value of \(r,\,\,{r_0}\)in the above equation and solve for the value of \(A\)

\(\begin{aligned}{}A = \left( {\frac{{7.5 \times {{10}^{ - 13}}\;{\rm{m}}}}{{1.2 \times {{10}^{ - 15}}\;{\rm{m}}}}} \right)\\ = 2.4 \times {10^8}{\rm{u}}A\\ = 2.4 \times {10^8}{\rm{u}}\end{aligned}\)

Therefore, value of \(A\)is \(2.4 \times {10^8}{\rm{u}}\).

b)

The unreasonable about the result is that the value of atomic mass is vey high.

c)

The radius of nucleus is very high.