Final answer:
In chemistry, significant figures indicate precision in measurements. The number of significant figures for the given measurements are two for 52,000,000 km, four for 3,000. g, three for 0.0000750 m, two for 1.7 × 10^-6 cm, and one for 3 × 10^8 g.
Step-by-step explanation:
When counting significant figures in a measurement, the rules we apply include:
Non-zero digits are always significant.
Any zeros between significant digits are significant.
Leading zeros (those before the first non-zero digit) are not significant.
Trailing zeros in a number with a decimal point are significant.
Trailing zeros in a number without a decimal point are ambiguous and may or may not be significant unless expressed in scientific notation.
Now, let's consider each measurement:
52,000,000 km has two significant figures since there is no decimal place, and we cannot be sure if the zeros are significant without further context or notation.
3,000. g has four significant figures because the decimal point indicates that all zeros are significant.
0.0000750 m has three significant figures; the first four zeros are leading and not significant, but the three numbers after are significant.
1.7 × 10-6 cm also has two – all non-zero numbers are significant, and the exponent doesn't affect the count.
3 × 108 g has one significant figure since there are no digits following the three.
In summary:
52,000,000 km = 2 significant figures
3,000. g = 4 significant figures
0.0000750 m = 3 significant figures
1.7 × 10-6 cm = 2 significant figures
3 × 108 g = 1 significant figure