b
$1\,amu\, = \,1.66 \times \,{10^{ - 27}}\,\,kg\,$
$\therefore \,\,\,1\,\,amu\, = \,1.66 \times \,{10^{ - 24}}\,g\,\,\,(\because \,\,\,1\,kg\, = \,{10^3}\,g)$
$\therefore \,1\,\,g\,\, = \,\frac{1}{{1.66 \times {{10}^{ - 24}}\,\,}}\,\,amu$
$\therefore \,1\,\,g\,\, = \,6.02\, \times \,{10^{23}}\,\,amu$