c
\({\text{N}}_a^{ + {\text{10}}};\,\,Z = 11\,\,\) માટે

\(\,\,\,\frac{{{\text{1216}} = \frac{{\text{1}}}{{\text{R}}}\left( {\frac{{1 \times 4}}{3}} \right)}}{{x = \frac{1}{{R(121)}}\left( {\frac{{1 \times 4}}{3}} \right)}}\,\,\,\,\, \Rightarrow \,\,\,\,\,\frac{{1216}}{x} = 121\,\,\,\, \Rightarrow \,\,\,\,x = \frac{{1216}}{{121}}\,\,\, \Rightarrow \,\,x = 10\,\mathop A\limits^o \)