Answer:
a) 4 sig. figs.
b) 4 sig. figs.
c) 1 sig. fig.
d) 2 sig. figs.
Step-by-step explanation:
First, let's remember some rules of significant figures:
1. All nonzero digits in a measurement are significant.
2. Zeros that appear between other nonzero digits are always significant.
3. Zeros that appear in front of all of the nonzero digits are called left-end zeros. Left-end zeros are never significant.
4. Zeros that appear after all nonzero digits are called right-end zeros. Right-end zeros in a number that lacks a decimal point are not significant.
5. Right-end zeros in a number with a decimal point are significant. This is true whether the zeros occur before or after the decimal point.
Now, let's answer for each measurement:
a) 4867 mi: based on rule (1), we have 4 significant figures.
b) 2901 g: based on rule (2), we have 4 significant figures.
c) 0.0000003 cm: based on rule (3), we have 1 significant figure.
d) 4.6 x 10^19 atoms: in a scientific notation, we just take into account the number that precedes the 10 with its exponent, which in this case is 4.6, so based on rule (1), we have 2 significant figures.