#### Answer

(a) $7.68~g$
This measurement has three significant figures.
(b) $0.420~kg$
This measurement has three significant figures.
(c) $0.073~m$
This measurement has two significant figures.
(d) $7.68\times 10^5~g$
This measurement has three significant figures.
(e) $4.20\times 10^3~kg$
This measurement has three significant figures.
(f) $7.3\times 10^{-2}~m$
This measurement has two significant figures.
(g) $2.300\times 10^4~s$
This measurement has four significant figures.

#### Work Step by Step

We can find the number of significant figures in each measurement.
(a) $7.68~g$
This measurement has three significant figures.
(b) $0.420~kg$
This measurement has three significant figures.
(c) $0.073~m$
This measurement has two significant figures.
(d) $7.68\times 10^5~g$
This measurement has three significant figures.
(e) $4.20\times 10^3~kg$
This measurement has three significant figures.
(f) $7.3\times 10^{-2}~m$
This measurement has two significant figures.
(g) $2.300\times 10^4~s$
This measurement has four significant figures.