An ion is formed
- A. By either adding or subtracting protons from the atom.
- B. By either adding or subtracting electrons from the atom
- C. By either adding or subtracting neutrons from the atom.
- D. All of the above are true.
Correct Answer: A
Rationale: The correct answer is A: By either adding or subtracting protons from the atom. An ion is formed when an atom gains or loses electrons, leading to an unequal number of protons and electrons. Protons determine the atom's identity, so changing the number of protons would result in a different element. This process results in the formation of ions with a positive charge if protons are added or a negative charge if protons are subtracted. Choices B and C are incorrect because adding or subtracting electrons or neutrons does not change the fundamental identity of the atom, only its charge or mass. Choice D is incorrect as not all options are true for ion formation.
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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.
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.
Which of the following is an example of a quantitative observation?
- A. The piece of metal is longer than the piece of wood.
- B. Solution 1 is much darker than solution
- C. The liquid in beaker A is blue.
- D. The temperature of the liquid is 60°C.
Correct Answer: A
Rationale: The correct answer is A because it involves a measurable quantity (length) that can be expressed numerically. This is a quantitative observation as it can be described with numbers. Choices B and C describe qualities (color and appearance) which are qualitative observations. Choice D provides a quantitative measurement (temperature) but it is not an observation, rather a measurement.
409 Kelvin equals
- A. 136°F
- B. 273°F
- C. 682°F
- D. 136°C
Correct Answer: D
Rationale: To convert Kelvin to Celsius, subtract 273. So, 409K - 273 = 136°C. Choice D is correct. Choice A (136°F) is incorrect because it's a Fahrenheit conversion. Choice B (273°F) is incorrect, as it doesn't convert Kelvin to Fahrenheit. Choice C (682°F) is incorrect, as it's double the incorrect Fahrenheit conversion.
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.