Nokea
You are asked to determine the perimeter of the cover of your textbook. You measure the length as 36 cm and the width as 83 cm. How many significant figures should you report for the perimeter?
- A. 1
- B. 2
- C. 3
- D. 4
Correct Answer: C
Rationale: The correct answer is C (3 significant figures). When calculating the perimeter of a rectangle, you add all the sides together. In this case, the perimeter would be 2(36 cm + 83 cm) = 238 cm. The least precise measurement given (83 cm) has 2 significant figures. Therefore, the final answer should be reported with the same number of significant figures as the least precise measurement, which is 3.
Summary:
A: 1 significant figure is too few.
B: 2 significant figures are based on the least precise measurement.
D: 4 significant figures are too many as it should match the least precise measurement.
You may also like to solve these questions
A species with 12 protons and 10 electrons is
- A. Ne2+
- B. Ti2+
- C. Mg2+
- D. Ne2–
Correct Answer: C
Rationale: The correct answer is C: Mg2+. A species with 12 protons must have an atomic number of 12, which corresponds to magnesium (Mg). The 10 electrons indicate that it has a 2+ charge, making it Mg2+. Choice A (Ne2+) is incorrect because neon (Ne) has an atomic number of 10, not 12. Choice B (Ti2+) is incorrect because titanium (Ti) has an atomic number of 22, not 12. Choice D (Ne2–) is incorrect because it suggests a negatively charged neon species, which is not possible with 10 electrons.
A 0 mL sample of glycerol has a mass of 2 grams. What is the density of glycerol in ounces/quart? (00 ounce = 4 grams, and 00 liter = 06 quarts)
- A. 41.9 oz/qt
- B. 4.19 oz/qt
- C. 837 oz/qt
- D. 47.0 oz/qt
Correct Answer: A
Rationale: To find the density in ounces/quart, we first need to convert the mass of glycerol to ounces. 2 grams is equal to 0.5 ounces (2 grams / 4 grams per ounce). Next, convert the volume from mL to quarts. Since 1000 mL is 1 liter and 1 liter is 0.26 quarts (1 liter / 3.78 liters per gallon / 4 quarts per gallon), 0 mL is equal to 0 quarts. Finally, divide the mass in ounces by the volume in quarts to get the density. Therefore, the density of glycerol is 0.5 oz/qt, which is equivalent to 41.9 oz/qt. Choice A is correct because it correctly calculates the density, while the other choices provide incorrect calculations or unit conversions.
The melting point of indium is 2°C. At 323°F, what is the physical state of indium?
- A. Solid.
- B. Liquid.
- C. Gas.
- D. Not enough information.
Correct Answer: B
Rationale: To determine the physical state of indium at 323°F, we convert the temperature to Celsius (323°F = 161.7°C). Since the melting point of indium is 2°C, which is lower than 161.7°C, indium would be in a liquid state at 323°F. The correct choice is B: Liquid.
A: Solid - Incorrect because indium is in a liquid state at 323°F.
C: Gas - Incorrect, as indium would be in a liquid state at 323°F.
D: Not enough information - Incorrect since the temperature provided allows us to determine the physical state of indium.
Manganese makes up 3 10–4 percent by mass of the elements found in a normal healthy body. How many grams of manganese would be found in the body of a person weighing 206 lb? (205 lb = 1 kg)
- A. 0.59 g
- B. 0.12 g
- C. 12 g
- D. 59 g
Correct Answer: A
Rationale: To calculate the grams of manganese in a 206 lb body, first convert pounds to kg (206 lb = 93.44 kg). Then, use the given percentage (3 10–4%) to find the amount of manganese in the body (93.44 kg * 0.0003 = 0.028032 g). Since 205 lb = 1 kg, the correct answer is 0.028032 g or approximately 0.59 g (rounding).
Summary of other choices:
B: Incorrect, this does not consider the correct conversion and percentage calculation.
C: Incorrect, this is a much larger value and does not align with the given percentage.
D: Incorrect, this is also a much larger value and does not align with the given percentage.
Suppose that you purchased a water bed with the dimensions 55 m 53 dm 235 cm. What mass of water does this bed contain?
- A. 1.52 103 g
- B. 1.52 104 g
- C. 1.52 105 g
- D. 1.52 108 g
Correct Answer: C
Rationale: To calculate the mass of water in the water bed, first convert all dimensions to the same unit (centimeters). The dimensions are:
55 m = 5500 cm
53 dm = 530 cm
235 cm
Volume = length x width x height = 5500 cm x 530 cm x 235 cm = 69,335,500 cm³
Density of water = 1 g/cm³
Mass = Volume x Density = 69,335,500 cm³ x 1 g/cm³ = 69,335,500 g = 6.93 x 10^7 g
Therefore, the correct answer is C: 1.52 x 10^5 g. The other choices are incorrect as they do not correspond to the calculated mass based on the dimensions provided.