Ch.2 Assignment
Textbook Problems to Submit: 5, 35, 43, 63c, 75c, 83, 109, 115
5. When do zeros count as significant digits, and when don’t they count?
Zeros can count as significant digits when they are between non-zero digits or when they are at
the end of a decimal number. They are NOT counted as significant when they serve as
placeholders in a big number without a decimal point.
35. Express each number in decimal notation:
a. 6.022×10^23 (number of carbon atoms in 12.01g of carbon) =
602,200,000,000,000,000,000,000
b. 1.6×10^−19 C (charge of a proton in coulombs) = 0.00000000000000000016
c. 2.99×10^8 m/s (speed of light) = 299,000,000 m/s
d. 3.44×10^2 m/s (speed of sound) = 344 m/s
43. For each measured quantity, underline the zeros that are significant and draw an X through
the zeros that are not:
a. 0. 00 5 0 5 0 m -> Significant: 5050;
b. 0. 00000000000000 6 0 s -> Significant: 60;
c. 22 0 ,1 0 3 kg -> Significant: 220,103;
d. 0.001 0 8 in. -> Significant: 108;
63c. Correct any answers that have the incorrect number of significant figures:
8475.45−34.899=8439.55
8475.45−34.899= 8439.55 (rounded to the correct number of significant figures)
75c. Perform each conversion:
825 yd→kilometers
825yd×(0.9144m/1yd)×(1000m/1km)≈ 0.752 km
