Chapter 1, Problem 1.75E

A person weighed 15 pennies on a balance and recorded the following masses: 3.112 g 3.109 g 3.059 g 2.467 g 3.079 g 2.518 g 3.129 g 2.545 g 3.050 g 3.053 g 3.054 g 3.072 g 3.081 g 3.131 g 3.064 g Curious about the results, he looked at the dates on each penny. Two of the light pennies were minted in 1983 and one in 1982. The dates on the 12 heavier pennies ranged from 1970 to 1982. Two of the 12 heavier pennies were minted in 1982. a. Do you think the Bureau of the Mint changed the way it made pennies? Explain. b. The person calculated the average mass of the 12 heavy pennies. He expressed this average as 3.0828 g 0.0482 g. What is wrong with the numbers in this result, and how should the value be expressed?

What is the difference in surface area between two circles, one of radius 7.98 cm, the other of radius 8.50 cm? The surface area of a circle of radius r is r2. Obtain the result to the correct number of significant figures.

Molecular distances are usually given in nanometers (1 nm = 1 109 m) or in picometers (1 pm = 1 1012 m). However, the angstrom () unit is sometimes used, where 1 = 1 1010 m. (The angstrom unit is not an SI unit.) If the distances between the Pt atom and the N atom in the cancer chemotherapy drug cisplatin is 1.97 , What is this distances in nanometers? In picometers?

Express the measurements to the requested number of significant figures. (a) 96,485 J/C to three significant figures (b) 2.9979 g/cm3 to three significant figures (c) 0.0597 mL to one significant figure (d) 6.626 1034 kg to two significant figures

The first measurement of sea depth was made in 1840 in the central South Atlantic, where a plummet was lowered 2425 fathoms. What is this depth in meters? Note that 1 fathom = 6ft, 1 ft = 12 in., and 1 in. = 2.54 102 m. (These relations are exact.)

Although the preferred SI unit of area is the square meter, land is often measured in the metric system in hectares (ha). One hectare is equal to 10,000 m2. In the English system, land is often measured in acres (1 acre = 160 rod2). Use the exact conversions and those given in Exercise 47 to calculate the following. a. 1 ha = __________ km2 b. The area of a 5.5-acre plot of land in hectares, square meters, and square kilometers c. A lot with dimensions 120 ft by 75 ft is to be sold for 6500. What is the price per acre? What is the price per hectare?

A solution is prepared by dissolving table salt, sodium chloride, in water at room temperature. a Assuming there is no significant change in the volume of water during the preparation of the solution, how would the density of the solution compare to that of pure water? b If you were to boil the solution for several minutes and then allow it to cool to room temperature, how would the density of the solution compare to the density in part a? c If you took the solution prepared in part a and added more water, how would this affect the density of the solution?

The total length of all the DNA molecules contained in a human body is 1 1010 miles. The population of the United States is about 300 million. What is the total length of all the DNA of the U.S. population in lightyears? (A light year is the distance that light travels in a year and is 9.46 1015 m.)

1.89 Imagine that you place a cork measuring 1.30cm4.50cm3.00cm in a pan of water. On top of this cork, you place a small cube of lead measuring 1.15 cm on a side. Describe how you would determine if the combination of the cork and lead cube will still float in the water. Note any information you would need to look up to answer the question.