Nokea
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.
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Order the four metric prefixes from smallest to largest.
- A. nano- < milli- < centi- < kilo-
- B. milli- < nano- < centi- < kilo-
- C. kilo- < centi- < nano- < milli-
- D. kilo- < centi- < milli- < nano-
Correct Answer: A
Rationale: The correct order is A: nano- < milli- < centi- < kilo-. The rationale is as follows:
1. Start from the smallest prefix, which is nano- representing 10^-9.
2. Moving up, milli- comes next representing 10^-3, which is larger than nano-.
3. Following milli- is centi- representing 10^-2, larger than milli-.
4. Lastly, kilo- is the largest prefix representing 10^3, making it the largest of the four options.
Therefore, the correct order is nano- < milli- < centi- < kilo-.
The other choices are incorrect because they do not follow the correct increasing order of magnitude for the metric prefixes.
How many significant figures should be reported for the difference between 6172 mL and 57 mL?
- A. 1
- B. 2
- C. 3
- D. 4
Correct Answer: B
Rationale: To determine the significant figures in the difference between 6172 mL and 57 mL, subtract the numbers: 6172 mL - 57 mL = 6115 mL. The answer should have the same number of decimal places as the number with the fewest decimal places in the subtraction, which is 57 mL. Hence, the correct answer is 2 significant figures. Choice A is incorrect because it is too low as it does not account for the 1 in the tens place of 57 mL. Choice C is incorrect as it is too high because the answer does not have that many significant figures. Choice D is incorrect as it also overestimates the number of significant figures in the difference.
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.
Considering the plot of total mass (y-axis) versus volume (x-axis), which of the following is true?
- A. The plot should be rather linear because the slope measures the density of a liquid.
- B. The plot should be curved upward because the slope measures the density of a liquid.
- C. The plot should be curved upward because the mass of the liquid is higher in successive trials.
- D. The plot should be linear because the mass of the beaker stays constant.
Correct Answer: A
Rationale: The correct answer is A. The plot of total mass versus volume should be rather linear because the slope measures the density of a liquid. This is because density is defined as mass divided by volume (density = mass/volume). Therefore, when mass is plotted against volume, the slope of the line represents the density of the liquid. A linear relationship between mass and volume indicates that the density remains constant.
Summary of other choices:
B: The plot being curved upward due to slope measuring density is incorrect.
C: The plot being curved upward due to mass being higher in successive trials is incorrect.
D: The plot being linear because the mass of the beaker stays constant is incorrect.
The first scientist to show that atoms emit any negative particles was
- A. J. J. Thomson
- B. Lord Kelvin
- C. Ernest Rutherford
- D. William Thomson
Correct Answer: A
Rationale: Step-by-step rationale:
1. J.J. Thomson discovered the electron in 1897 through his cathode ray experiment.
2. Electrons are negatively charged particles emitted by atoms.
3. This groundbreaking discovery proved atoms emit negative particles.
4. Therefore, J.J. Thomson is the correct answer.
Summary:
- Lord Kelvin focused on thermodynamics, not subatomic particles.
- Ernest Rutherford discovered the nucleus, not electrons.
- William Thomson, also known as Lord Kelvin, did not directly contribute to the discovery of negative particles emitted by atoms.