Problem 38
Classify the following as qualitative or quantitative statements, giving your reasons. (a) The sun is approximately 93 million mi from Earth. (b) Leonardo da Vinci was a better painter than Michelangelo. (c) Ice is less dense than water. (d) Butter tastes better than margarine. (e) A stitch in time saves nine.
Problem 39
Determine whether each of the following describes a physical change or a chemical change: (a) The helium gas inside a balloon tends to leak out after a few hours. (b) A flashlight beam slowly gets dimmer and finally goes out. (c) Frozen orange juice is reconstituted by adding water to it. (d) The growth of plants depends on the sun's energy in a process called photosynthesis. (e) A spoonful of salt dissolves in a bowl of soup.
Problem 40
A student pours \(44.3 \mathrm{~g}\) of water at \(10^{\circ} \mathrm{C}\) into a beaker containing \(115.2 \mathrm{~g}\) of water at \(10^{\circ} \mathrm{C}\). What are the final mass, temperature, and density of the combined water? The density of water at \(10^{\circ} \mathrm{C}\) is \(1.00 \mathrm{~g} / \mathrm{mL}\).
Problem 41
A \(37.2-\mathrm{g}\) sample of lead \((\mathrm{Pb})\) pellets at \(20^{\circ} \mathrm{C}\) is mixed with a 62.7 -g sample of lead pellets at the same temperature. What are the final mass, temperature, and density of the combined sample? The density of \(\mathrm{Pb}\) at \(20^{\circ} \mathrm{C}\) is \(11.35 \mathrm{~g} / \mathrm{cm}^{3}\).
Problem 42
Comment on whether each of the following statements represents an exact number: (a) 50,247 tickets were sold at a sporting event. (b) \(509.2 \mathrm{~mL}\) of water was used to make a birthday cake, (c) 3 dozen eggs were used to make a breakfast, (d) \(0.41 \mathrm{~g}\) of oxygen was inhaled in each breath, (e) Earth orbits the sun every 365.2564 days.
Problem 43
What is the advantage of using scientific notation over decimal notation?
Problem 44
What is the advantage of using scientific notation over decimal notation?
Problem 45
Distinguish between the terms accuracy and precision. In general, explain why a precise measurement does not always guarantee an accurate result.
Problem 46
Express the following numbers in scientific notation: (a) 0.000000027 , (b) 356 , (c) 47,764, (d) 0.096 .
Problem 47
Express the following numbers as decimals: (a) \(1.52 \times 10^{-2}\) (b) \(7.78 \times 10^{-8}\) (c) \(1 \times 10^{-6}\) (d) \(1.6001 \times 10^{3}\).
