Nokea
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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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.
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.
The agreement of a particular value with the true value is called
- A. accuracy
- B. error
- C. precision
- D. significance
Correct Answer: A
Rationale: The correct answer is A: accuracy. Accuracy refers to how close a measured value is to the true value. It indicates the absence of systematic errors. Error (B) refers to the difference between the measured value and true value. Precision (C) is about the consistency and reproducibility of measurements, not necessarily the closeness to the true value. Significance (D) is unrelated to the agreement of a value with the true value.
All of the following are true except:
- A. Ions are formed by adding electrons to a neutral atom.
- B. Ions are formed by changing the number of protons in an atom's nucleus.
- C. Ions are formed by removing electrons from a neutral atom.
- D. An ion has a positive or negative charge.
Correct Answer: B
Rationale: The correct answer is B because changing the number of protons in an atom's nucleus would result in a different element, not an ion.
A: True - adding or removing electrons forms ions.
C: True - removing electrons forms positively charged ions.
D: True - ions have a charge due to the imbalance of protons and electrons.
Generally, observed behavior that can be formulated into a statement, sometimesmathematical in nature, is called a(n)
- A. observation
- B. measuremen t
- C. theory
- D. natural law
Correct Answer: A
Rationale: The correct answer is A: observation. Observations are specific instances of behavior that can be described and formulated into statements, including mathematical ones. Measurements (choice B) involve quantifying observations. Theories (choice C) are broader explanations based on observations. Natural laws (choice D) are general principles derived from consistent observations. In this context, the term "observed behavior" specifically points to the act of witnessing and formulating statements about behavior, making choice A the most suitable option.