Fill in the blanks:
$(a)$ $\frac{1\,\mu m}{1\,fm} = \,....$
$(b)$ The number of significant figures in $0.0060$ is $....$
$(c)$ To study nanotechnology,the $....$ microscope has been developed.

(N/A) Since $1\,\mu m = 10^{-6}\,m$ and $1\,fm = 10^{-15}\,m$,then $\frac{10^{-6}}{10^{-15}} = 10^{9}$.
$(b)$ In the number $0.0060$,the leading zeros are not significant. The non-zero digit $6$ and the trailing zero after the decimal point are significant. Thus,there are $2$ significant figures.
$(c)$ The Scanning Tunneling Microscope $(STM)$ is used for the study of nanotechnology.